| 1. |
- Engström, Carl-Peter, 1945, et al.
(author)
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Functional status and well being in chronic obstructive pulmonary disease with regard to clinical parameters and smoking: a descriptive and comparative study.
- 1996
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In: Thorax. - 0040-6376. ; 51:8, s. 825-30
-
Journal article (peer-reviewed)abstract
- BACKGROUND: Self-assessment questionnaires which measure the functional and affective consequences of chronic obstructive pulmonary disease (COPD) give valuable information about the effects of the disease and may serve as important tools with which to evaluate treatment. METHODS: A cross sectional comparative study was performed between patients with COPD (n = 68), stratified according to pulmonary function, and a healthy control group (n = 89). A battery of well established clinical and quality of life measures (the Sickness Impact Profile (SIP), Mood Adjective Check List (MACL), and Hospital Anxiety and Depression scale (HAD)) was used to examine in which functional and affective aspects the patient group differed from the control group and how these measures related to pulmonary function and smoking habits. RESULTS: Compared with the controls, COPD affected functional status in most areas, not just those requiring physical activity. Forty six patients with forced expiratory volume in one second (FEV1) below 50% predicted showed particularly high levels of dysfunction in ambulation, eating, home management, and recreation/ pastimes (SIP). Despite this, their level of psychosocial functioning and mood status was little different from that of the healthy controls. Among the patients, a subgroup reported substantial psychological distress, but mood status was only weakly, or not at all, related to pulmonary function. Smoking habits did not affect functional status or well being. CONCLUSIONS: Quality of life is not significantly affected in patients with mild to moderate loss of pulmonary function, possibly due to coping and/or pulmonary reserve capacity. This suggests that generic self-assessment questionnaires are of limited value for detecting the early consequences of COPD. However, in later stages of the disease they are sensitive enough to discriminate between patients with different levels of pulmonary dysfunction. The low correlations between the indices of pulmonary function and the indices of affective status suggest that well being depends, to a large extent, on factors outside the clinical domain.
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| 2. |
- Engström, Carl-Peter, 1945, et al.
(author)
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Health-related quality of life in COPD: why both disease-specific and generic measures should be used.
- 2001
-
In: The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology. - 0903-1936. ; 18:1, s. 69-76
-
Journal article (peer-reviewed)abstract
- Although research has consistently demonstrated that chronic obstructive pulmonary disease (COPD) impairs health-related quality of life (HRQL), little agreement has been evidenced regarding the factors identified as contributing to impaired HRQL. The aim was to study such factors using well established generic and specific HRQL instruments. The patients (n=68) were stratified by forced expiratory volume in one second (FEV1) to represent a wide range of disease severity. Pulmonary function, blood gases and 6-min walking distance test (6MWD) were assessed. HRQL instruments included: St George's Respiratory Questionnaire (SGRQ), Sickness Impact Profile (SIP), Hospital Anxiety and Depression Scale and Mood Adjective Check List. The strength of the impact of COPD on HRQL was represented along a continuum ranging from lung function, functional status (physical and psychosocial) to wellbeing. Although correlations between FEV1 versus SGRQ total and SIP overall scores (r=-0.42 and -0.32) were stronger than previously reported, multiple regression analyses showed that lung function contributed little to the variance when dyspnoea-related limitation, depression scores and 6MWD were included in the models. These three factors were important to varying degrees along the whole range of HRQL. Physiological, functional and psychosocial consequences of chronic obstructive pulmonary disease are only poorly to moderately related to each other. The present study concludes that a comprehensive assessment of the effects of chronic obstructive pulmonary disease requires a battery of instruments that not only tap the disease-specific effects, but also the overall burden of the disease on everyday functioning and emotional wellbeing.
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| 3. |
- Engström, Carl-Peter, 1945, et al.
(author)
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Long-term effects of a pulmonary rehabilitation programme in outpatients with chronic obstructive pulmonary disease: a randomized controlled study.
- 1999
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In: Scandinavian journal of rehabilitation medicine. - 0036-5505. ; 31:4, s. 207-13
-
Journal article (peer-reviewed)abstract
- Fifty patients with severe chronic obstructive pulmonary disease (FEV1 < 50% pred.) were randomized to a rehabilitation group and a control group. The rehabilitation group took part in an individualized multidisciplinary, outpatient 12-month rehabilitation programme. Exercise training was intensive during the first 6 weeks and was then gradually replaced by an individual home-training programme and booster sessions. Controls received the usual outpatient care. Positive effects were found in terms of maximum symptom-limited exercise tolerance and walking distance (13.5 and 12.1% increase, respectively) in the rehabilitation group compared with the controls. Quality of life measurements showed minor beneficial effects on the Sickness Impact Profile, indicating a higher level of activity. No effect was seen on the St George's Respiratory Questionnaire or the Mood Adjective Check List. Patients expressed their enthusiasm for the rehabilitation programme in a study-specific questionnaire.
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| 4. |
- Engström, Carl-Peter, 1945, et al.
(author)
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Reliability and validity of a Swedish version of the St George's Respiratory Questionnaire.
- 1998
-
In: The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology. - 0903-1936. ; 11:1, s. 61-6
-
Journal article (peer-reviewed)abstract
- The St George's Respiratory Questionnaire (SGRQ) was designed to measure quality of life (QoL) in obstructive pulmonary disease. Its reliability, validity and sensitivity have been demonstrated. The aim was to develop a Swedish version of the SGRQ and to confirm its scaling and clinical properties. The SGRQ was adapted for Swedish conditions following a translation-backtranslation procedure. The psychometric and clinical evaluation included 68 patients with chronic obstructive pulmonary disease (COPD). Supplementary QoL, clinical and physiological data were collected. A follow-up study was performed 1 yr later. Correlation analysis used a multitrait-multimethod model. Internal consistency reliability and discriminant validity were documented by performing a multitrait analysis. The results confirmed expected levels of associations. Correlation coefficients between the SGRQ total score and the Sickness Impact Profile Total score (a generic health measure), forced expiratory volume in one second (FEV1) and 6 min walking distance were 0.69, -0.42 and -0.61 respectively. The pattern of correlations in the Swedish data set was very similar to that of the original. The stability of the SGRQ scores was confirmed at follow-up after 1 yr. The reliability was satisfactory, with Cronbach's alpha coefficients >0.80 for the SGRQ and its subdimensions. In conclusion, the Swedish version of the St George's Respiratory Questionnaire is reliable, valid and compares well with the corresponding tests of the original version.
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| 5. |
- Persson, Lars-Olof, 1951, et al.
(author)
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Life values in patients with COPD: relations with pulmonary functioning and health related quality of life.
- 2005
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In: Quality of life research : an international journal of quality of life aspects of treatment, care and rehabilitation. - 0962-9343. ; 14:2, s. 349-59
-
Journal article (peer-reviewed)abstract
- Theories of coping and response shift have suggested that emotional adaptation is related to value changes, e.g. a deemphasized importance of lost life values and an enlargement of the scope of values. Perceived attainment and importance of 82 life values were examined in 65 patients with chronic obstructive pulmonary disease (COPD) and related to clinical and Health-Related Quality of Life (HRQL) measures. The life values covered 10 dimensions--harmony, positive relations, involvement, mobility, communication, knowledge, responsibility, comfort, religion and health. Forty-six of the patients were followed up after 1 year. The patients with COPD were compared with a healthy control group, a group of neurologically impaired and a non-disabled group representing the general population. Significant congruence was found between importance and attainment ratings in all groups (correlations from 0.44 to 0.53), suggesting that both impaired and healthy persons tend to perceive that they have what they find important in life. Congruence was significantly related to mood (correlations from 0.28 to 0.40), but not to functional status or clinical data. Compared to the healthy responders, the patients with COPD had significantly lower attainment ratings in health, mobility, involvement, but no differences were found for importance ratings. No evidence was found that they had replaced unattainable values with new available values, and no changes over time of perceived values were found. This suggests that patients with COPD do not seem to adapt by means of changing their value orientation.
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| 6. |
- Balestra, F., et al.
(author)
-
NANOSIL network of excellence-silicon-based nanostructures and nanodevices for long-term nanoelectronics applications
- 2008
-
In: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 11:5-6, s. 148-159
-
Journal article (peer-reviewed)abstract
- NANOSIL Network of Excellence [NANOSIL NoE web site < www.nanosil-noe.eu >], funded by the European Commission in the 7th Framework Programme (ICT-FP7, no 216171), aims at European scale integration of the excellent European research laboratories and their capabilities in order to strengthen scientific and technological excellence in the field of nanoelectronic materials and devices for terascale integrated circuits (ICs), and to disseminating the results in a wide scientific and industrial community. NANOSIL is exploring and assessing the science and technological aspects of nanodevices and operational regimes relevant to the n+4 technology node and beyond. It encompasses projects on nanoscale CMOS and beyond-CMOS. Innovative concepts, technologies and device architectures are proposed-with fabrication down to the finest features, and utilising a wide spectrum of advanced deposition and processing capabilities, extensive characterization and very rigorous device modeling. This work is carried out through a network of joint processing, characterization and modeling platforms. This critical interaction strengthens European integration in nanoelectronics and will speed up technological innovation for the nanoelectronics of the next two to three decades.
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| 7. |
- Bengtsson, Stefan, 1961, et al.
(author)
-
Characterisation of interface electron state distributions at directly bonded silicon/silicon interfaces
- 1990
-
In: ESSDERC 90. 20th European Solid State Device Research Conference. ; , s. 1-
-
Conference paper (peer-reviewed)abstract
- Measurement methods for characterizing the electrical properties of directly bonded Si/Si n/n-type or p/p-type interfaces are presented. The density of interface states in the bandgap of the semiconductor and the density of interface charges at the bonded interface are determined from measurements of current and capacitance vs. applied voltage
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| 8. |
- Bengtsson, Stefan, 1961, et al.
(author)
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Charge densities at silicon interfaces prepared by wafer bonding
- 1990
-
In: 1990 IEEE SOS/SOI Technology Conference.. ; , s. 77-
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Journal article (peer-reviewed)abstract
- It is found that Si/Si and Si/SiO2 interfaces exhibit different interface charge properties when bonded at comparable temperatures and surface treatments. Thermally grown oxides were bonded to bare silicon surfaces and the bonded Si/SiO2 interface was investigated on MOS-structures by the C-V technique. Interfaces prepared at temperatures in the range 900-1100°c exhibited U-shaped interface state densities. Si/Si samples were prepared using a hydrophilizing surface treatment before wafer bonding. At the same annealing temperatures, the interface state densities of the bonded Si/Si interfaces were in the range 1011-1013 cm-2 eV-1. Si/Si interfaces are found to be very sensitive to prebond chemical treatment, while Si/SiO2 interfaces are not. Native oxides at bonded silicon interfaces have a more pronounced influence on Si/Si interfaces than on Si/SiO2 interfaces
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| 9. |
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| 10. |
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| 11. |
- Bengtsson, Stefan, 1961, et al.
(author)
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IC process compatible preparation of silicon interfaces using the silicon-to-silicon direct bonding method
- 1989
-
In: ESSDERC '89. 19th European Solid State Devices Research Conference. ; , s. 353-
-
Conference paper (peer-reviewed)abstract
- Silicon/silicon interfaces were prepared by wafer bonding using the silicon-to-silicon direct bonding method. Silicon/silicon interfaces (n/n-type) with excellent electric properties were prepared, by using hydrophobic wafer surfaces, at temperatures in the range of 700°C to 1000°C. The influence of the bonded interface on device characteristics of bonded p+n junctions prepared at low temperatures was seen as n-factors larger than 2 at forward bias. A correlation between n-factors and the density of states in the bandgap was found. In hydrophilic samples, the density of voids at the bonded interface was determined mainly in the contacting of the wafer surfaces at room temperature. Compared to hydrophilic samples, hydrophobic samples were held together at a smaller fraction of the area before heat treatment. After the heat treatments, no difference in the density of voids was found
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| 12. |
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| 13. |
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| 14. |
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| 15. |
- Bengtsson, Stefan, 1961, et al.
(author)
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Oxide degradation of wafer bonded MOS capacitors following Fowler-Nordheim electron injection
- 1992
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In: Proceedings of the First International Symposium on Semiconductor Wafer Bonding: Science, Technology and Applications. ; , s. 339-
-
Conference paper (peer-reviewed)abstract
- The degradation of wafer bonded silicon dioxides as a result of Fowler-Nordheim electron injection has been studied. The samples were MOS capacitors with wafer bonded SiO2-SiO2 interfaces at the oxide center. The charge trapping in the oxide and the Si-SiO2 interface state generation were monitored as a function of injected charge and compared to reference MOS capacitors without bonded interfaces. A larger change in the oxide charge was found in the bonded capacitors as compared to the reference structures. The centroid of trapped negative oxide charge was found to be located close to the SiO2-SiO2 interface in the bonded structures, while the reference structures exhibited centroids close to the injecting contact. The electron injection caused approximately the same generation of interface states in both groups of capacitors
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| 16. |
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| 17. |
- Bonmann, Marlene, 1988, et al.
(author)
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Effect of oxide traps on channel transport characteristics in graphene field effect transistors
- 2017
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In: Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures. - : American Vacuum Society. - 2166-2754 .- 2166-2746. ; 35:1, s. 01A115-
-
Journal article (peer-reviewed)abstract
- A semiempirical model describing the influence of interface states on characteristics of gatecapacitance and drain resistance versus gate voltage of top gated graphene field effect transistors ispresented. By fitting our model to measurements of capacitance–voltage characteristics and relatingthe applied gate voltage to the Fermi level position, the interface state density is found. Knowing theinterface state density allows us to fit our model to measured drain resistance–gate voltagecharacteristics. The extracted values of mobility and residual charge carrier concentration arecompared with corresponding results from a commonly accepted model which neglects the effect ofinterface states. The authors show that mobility and residual charge carrier concentration differsignificantly, if interface states are neglected. Furthermore, our approach allows us to investigate indetail how uncertainties in material parameters like the Fermi velocity and contact resistanceinfluence the extracted values of interface state density, mobility, and residual charge carrierconcentration.
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| 18. |
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| 19. |
- Ducroquet, F., et al.
(author)
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Admittance spectroscopy of Si/LaLuO3 and Si/GdSiO MOS Structures (Invited)
- 2012
-
In: ECS Transactions. - : The Electrochemical Society. - 1938-5862 .- 1938-6737. ; 45:3, s. 103 - 117
-
Conference paper (peer-reviewed)abstract
- Interface states at the gate oxide/channel of metal oxide semiconductor (MOS) transistors generally result in detrimental effects on the device performance which need to be considered for the new generations of high-k dielectrics. In this paper, the admittance of Gadolinium silicate (GdSiO) and Lanthanum Lutetium oxide (LaLuO3) MOS capacitors were investigated as a function of the signal frequency, temperature and gate voltage. The Arrhenius plots of the peak pulsations extracted from the conductance spectra have been discussed on the bases of simulated data taking into account a distribution of the trap energy levels and a thermally enhanced capture cross-section. The consequences of a peaked interface state distribution on the evolution of activation energies are shown to lead to Arrhenius plots following the Meyer-Neldel Rule.
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| 20. |
- Engström, Lil, 1943-
(author)
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Möjligheter till lärande i matematik : Lärares problemformuleringar och dynamisk programvara
- 2006
-
Doctoral thesis (other academic/artistic)abstract
- This thesis presents the first Swedish empirical evidence on how teachers employ a dynamic mathematical software when teaching mathematics in upper secondary school. The study examines: a) How teachers formulate mathematical problems? b) How they use the experience the students have gained? and c) What use they make of the software’s potential? These questions are examined through classroom observations followed up by discussions with the teachers.The study comprises three teachers and shows that they have very different mathematical experiences and teaching skills. A questionnaire was sent to the teachers prior to the classroom visits to collect relevant background information; e.g., the teachers were asked to describe their teacher training, their view of mathematics and of how a dynamic software could contribute to their teaching.The results show that the teachers’ ability to pose thought-provoking openended problems is the most important factor as it significantly influences what the students learn. The way a mathematical problem is formulated could, in conjunction with a dynamic software, actually limit the students’ achievement.However, this study confirms that it could also provide an opportunity for students to discover new mathematical relations, draw conclusions, generalise and formulate hypotheses. This could in turn lead to an in formally proving a mathematical relation. A conclusion of the study is that to be successful, teachers need a good mathematical background with a firm knowledge base and an understanding of the software’s potential, but they also need the skill to formulate open-ended problems that will enable their students to work successfully with a dynamic mathematical software.
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| 21. |
- Engström, Olof, 1943, et al.
(author)
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A generalised methodology for oxide leakage current metric
- 2008
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In: Proceeding of 9th European Workshop on Ultimate Integration of Silicon (ULIS), Udine, Italy. - 9781424417308 ; , s. 167-
-
Conference paper (peer-reviewed)abstract
- From calculations of semiconductor interfacecharge, oxide voltage and tunneling currents for MOSsystems with equivalent oxide thickness (EOT) in therange of 1 nm, rules are suggested for making itpossible to compare leakage quality of different oxideswith an accuracy of a factor 2 – 3 if the EOT is known.The standard procedure suggested gives considerablybetter accuracy than the commonly used method todetermine leakage at VFB+1V for n-type and VFB-1V forp-type substrates.
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| 22. |
- Engström, Olof, 1943
(author)
-
A model for internal photoemission at high-k oxide/silicon energy barriers
- 2012
-
In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 112:6
-
Journal article (peer-reviewed)abstract
- A model has been developed to describe the emission of electrons from silicon across the oxide energy barrier of metal-oxide-silicon structures. An optical absorption coefficient, exclusively describing the transmission of electrons which are emitted across the barrier, is split from the corresponding experimental quantity for the entire absorption range. This makes it possible to approximate the photo yield in terms of absorption coefficients and density of states without need for explicitly calculated matrix elements of optical transitions. Using this method, theoretical emission yield curves are found in good agreement with measured data. An important conclusion from this work is that values of oxide energy barrier heights should be extracted from different features of the yield data than most often done in the literature. This replaces a commonly used practice for determining the barrier heights, which is shown to be based on optical bulk properties of the silicon crystal.
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| 23. |
- Engström, Olof, 1943, et al.
(author)
-
Analysis of electron capture at oxide traps by electric field injection
- 2013
-
In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 102:21
-
Journal article (peer-reviewed)abstract
- Electron injection into oxide traps of metal/high-k oxide/interlayer/silicon structures is investigated by modeling. We demonstrate the influence on flat-band voltage by the sharpness of the interlayer/silicon interface and by the properties of traps in the oxide. Since charge carrier injection in this kind of structures may take place by two different processes simultaneously, excluding one or the other in the interpretation of data may lead to considerable erroneous results in extracted values of capture cross sections.
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| 24. |
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| 25. |
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| 26. |
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| 27. |
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| 28. |
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| 29. |
- Engström, Olof, 1943
(author)
-
Compensation effects at electron traps in semiconductors
- 2013
-
In: Monatshefte für Chemie. - : Springer Science and Business Media LLC. - 0026-9247 .- 1434-4475. ; 144:1, s. 73-82
-
Journal article (peer-reviewed)abstract
- The basic qualities for fulfilling the Meyer-Neldel rule (MNR) for thermal electron emission from semiconductor traps are investigated. A trap model including vibronic properties is used with varying entropy arising from the change in elasticity of the ionic part of the trap potential when an electron transition takes place. This gives rise to a system where the compensation effect originates from the increasing entropy change as a function of the enthalpy supply needed for the transition process in concord with Yelon-Movaghar theory. The entropy increase connects to a decrease in the activation energy for electron capture, which amplifies the compensation effect for MNR manifestation. By comparing with experimental data, the result achieved from the model clarifies the experimental observation of class partitioning for centers in GaAs, obeying the MNR. Furthermore, it is demonstrated that traps at metal-oxide-silicon interfaces, with the same properties as bulk traps following the MNR, give rise to capture cross-sections steeply increasing with the Gibbs free energy involved in carrier emission, as found by experiment.
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| 30. |
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| 31. |
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| 32. |
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| 33. |
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| 34. |
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| 35. |
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| 36. |
- Engström, Olof, 1943, et al.
(author)
-
Electrical characterization of bonding interfaces
- 1992
-
In: Proceedings of the First International Symposium on Semiconductor Wafer Bonding: Science, Technology and Applications. ; , s. 295-
-
Conference paper (peer-reviewed)abstract
- An overview is given on measurement techniques and results obtained for the characterization of bonded Si-Si, Si-SiO2 and SiO2-SiO2 interfaces. The electrical properties of Si-Si interfaces are found to be very similar to those of grain boundaries, which suggests a model where the current across the interface is limited by a potential barrier determined by charge carriers captures into electron states at the bonded interface. From current-voltage and capacitance-voltage measurements, the interface charge and its energy distribution can be determined. For bonded Si-SiO2 interfaces, energy states distributions are obtained by capacitance voltage technique with midgap densities in the region at or above 5 1010 eV-1 cm-2. Interfaces between two bonded SiO2 layers exhibit an increased concentration of electron traps
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| 37. |
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| 38. |
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| 39. |
- Engström, Olof, 1943, et al.
(author)
-
Electron capture at InAs/GaAs quantum dots
- 2004
-
In: 8th International Conference on Nanometer Scale Science and Technology, Venice, Italy, 2004.
-
Conference paper (peer-reviewed)
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| 40. |
- Engström, Olof, 1943, et al.
(author)
-
Electron capture cross sections of InAs/GaAs quantum dots
- 2004
-
In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 85:14, s. 2908-2910
-
Journal article (peer-reviewed)abstract
- The thermal emission rates of electrons from InAs/GaAs quantum dots were measured, to found the capture cross sections in the extremely high region of 10-11-10-10 cm2. An additional method based on a static measurement at thermal equilibrium was used where the Fermi level was positioned at the free energy level of the quantum dot s shell. A Schottky diode with a plane of QDs grown in its depletion region and back-biased in such a way that the Fermi level coincides with the electron energy level. The Fermi level passes the lowest energy level of the QD, at the voltage marked by Vp in the graphs.
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| 41. |
- Engström, Olof, 1943
(author)
-
Electron states in MOS systems (Invited)
- 2011
-
In: ECS Transactions. - : The Electrochemical Society. - 1938-5862 .- 1938-6737. - 9781566778657 ; 35:4, s. 19 -38
-
Conference paper (peer-reviewed)abstract
- The properties of charge carrier traps in the oxide bulk, at high-k/silicon transition regions, at the silicon interface and as dipoles are discussed from physical and electrical perspectives. In order to elucidate the charging properties of oxide traps, the statistical mechanics for occupation is derived based on a constant pressure ensemble and used to interpret the influence of negative-U states occurring in high-k oxides. For the transition region close to the silicon interface, the existence of unstable traps in the continuous shift of the energy bands between SiO2 and HfO2 is pointed out. The physical background for electrical measurements on interface states is examined and, finally, dipoles constituted by traps in high-k dielectrics for regulating threshold voltage of MOS transistors are considered.
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| 42. |
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| 43. |
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| 44. |
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| 45. |
- Engström, Olof, 1943
(author)
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Foreword
- 2010
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In: Solid-State Electronics. - : Elsevier BV. - 0038-1101. ; 54:2, s. 85-85
-
Journal article (other academic/artistic)
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| 46. |
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| 47. |
- Engström, Olof, 1943, et al.
(author)
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Gate stacks
- 2013
-
In: Nanoscale CMOS: Innovative Materials, Modeling and Characterization. - : Wiley. ; , s. 23 - 67
-
Book chapter (other academic/artistic)
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| 48. |
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| 49. |
- Engström, Olof, 1943, et al.
(author)
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Influence of interlayer properties on the characteristics of high-k gate stacks
- 2012
-
In: Solid-State Electronics. - : Elsevier BV. - 0038-1101. ; 75, s. 63-68
-
Journal article (peer-reviewed)abstract
- The significance of interface sharpness between interlayers and high-k oxides for the properties of transistor gate-stacks has been investigated. Energy band variation in the oxide is calculated by using literature data for the HfO2/SiO2 interface, assuming two different cases for the interface plane: flat with a gradual depth variation of k-value and rough with an abrupt change of k. We demonstrate that the capacitive properties are similar, whereas tunneling properties considerably differ between the two cases. Furthermore, depth distributions of tunneling effective mass and dielectric constant have a substantial influence on the probability for charge carrier tunneling through the oxide stack and for the determination of capacitance equivalent oxide thickness (CET).
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| 50. |
- Engström, Olof, 1943, et al.
(author)
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Internal photoemission technique for high-k oxide/semiconductor band offset determination: The influence of semiconductor bulk properties
- 2014
-
In: 44th European Solid-State Device Research Conference, ESSDERC 2014, Palazzo del CasinoVenezia Lido, Italy, 22-26 September 2014. - 1930-8876. - 9781479943784 ; , s. 369-372
-
Conference paper (peer-reviewed)abstract
- A method for extracting energy band alignment of metal/high-k oxide/semiconductor structures from internal photoemission experiments is discussed by modeling the excitation and relaxation processes taking place in the semiconductor at photon irradiation. Classical literature data on photoemission of electrons from silicon and germanium surfaces into vacuum is compared with more recently published data on HfO2/Si and HfO2/Ge structures to identify characteristic features of photoelectric yield. We find that a dominating structure of such spectra, which often has been assumed to originate from the oxide barrier, derives from the energy dependence of absorption coefficient and mean free paths of excited electrons. Our results indicate that most IPE data on high-k oxide/silicon and germanium structures need re-interpretation.
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