| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Semchuk, O. Yu., et al.
(author)
-
Features of coherent laser beams interaction with condensed matter
- 2004
-
In: Appl. Surf. Sci.. - : Elsevier BV. - 0169-4332. ; 234:1-4, s. 415-421
-
Journal article (peer-reviewed)abstract
- Some mechanisms of formation of laser-induced periodic surface and bulk structures in condensed matter are considered. Their influence on optical properties of semiconductors is investigated. It is shown that under action of coherent laser beams (CLBs) a grating of the refraction index arises in semiconductors. The models featuring this effect are offered. The relevant theoretical calculations confirming occurrence the new phenomenon — appearance of a grating of the refractive index in semiconductors in a field of CLBs — were carried out. It is shown that in ferromagnetic semiconductors (FMSC) with a laser-induced grating of the magnon temperature one probably deals with occurrence of the nonlinearity of the refraction index caused by the nonlinearity of FMSC magnetic susceptibility and one should observe oscillations of a refraction index, which will result in occurrence of complementary darkened areas.
|
|
| 5. |
- Semchuk, O. Yu., et al.
(author)
-
Features of transport phenomenas in magnetic semiconductors with laser-induced periodic nanostructures
- 2007
-
In: Materials Science & Engineering. - : Elsevier BV. - 0921-5093 .- 1873-4936 .- 0928-4931 .- 1873-0191. ; 27:5-8, s. 1360-1363
-
Journal article (peer-reviewed)abstract
- The mechanisms of formation of the laser-induced periodic surface and bulk nanostructures in magnetic semiconductors are considered. Their influence on transport phenomena in ferromagnetic semiconductors (FMSC) is investigated. It is shown that under action of laser beams (LB) a laser-induced periodic nanostructures — gratings of the electron and magnon temperatures, electron concentration and electric fields arises in FMSC. It is determined, that the illuminating of an external surface of the FMSC by several LB results in an emerging new effect — appearance of a dropping site on the voltage-current characteristic (VCC) of the FMSC with the static laser-induced periodic nanostructures. This effect can only be observed for the carrier concentration n ≥ 1018 cm−3, since for smaller concentration the contribution of an additional current caused by the presence of the laser-induced periodic nanostructures will be insignificant.
|
|
| 6. |
- Semchuk, O. Yu, et al.
(author)
-
Laser ablation lithography on thermoelectric semconductor
- 2006
-
In: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 252:13, s. 4759-4762
-
Journal article (peer-reviewed)abstract
- In this paper, experimental results of the investigation of the periodic structure on thermoelectric semiconductor Cu2Se are presented. Periodic structures were formed on surfaces of semiconductors due to multi-beam interaction of Q-switched Nd:YAG laser, which was operated in the lowest order of Gaussian mode and pulse duration 7 ns. Surface temperature evolution and transient reflectivity are studied during laser treatment. Creation of Cu islands in the maximal intensity of interference pattern was found.
|
|
| 7. |
- Svensson, Bengt Gunnar, et al.
(author)
-
Hydrothermally Grown Single-Crystalline Zinc Oxide; Characterization and Modification
- 2007
-
In: MRS Proceedings Volume 1035 / 2007. - Warrendale, PA, USA : Materials Research Society.
-
Conference paper (other academic/artistic)abstract
- An overview of our recent results on characterization and modification of high-resistivity n-type bulk zinc oxide samples, grown by hydrothermal techniques, is given. Three specific topics are addressed; (i) the role of lithium (Li) as an electrically compensating impurity, (ii) extrinsic n-type doping by hydrogen implantation, and (iii) influence of annealing conditions on deep band emission. In (i), furnace annealing of as-grown samples at temperatures above ∼800 °C is shown to cause out-diffusion of residual Li impurities and concurrently, the resistivity decreases. After annealing at 1400 °C, a resistivity close to 10−1 Ωcm is obtained and the Li content is reduced from above 1017 cm−3 to the mid 1015 cm−3 range, providing evidence for the crucial role of Li as an electrically compensating impurity. For ion-implanted samples, vacancy clusters evolve during post-implant flash lamp annealing (20 ms duration) and these clusters appear to trap and deactivate Li with a resulting improvement of the n-type conductivity. However, these clusters have a limited stability and start to dissociate already after 1h at 900 °C, accompanied by a decrease in the conductivity. For topic (ii), n-type doping by hydrogen implantation is shown to enhance the conductivity by about 5 orders of magnitude already in the as-implanted state. Despite substantial loss of hydrogen, the conductivity remains stable, or even increases, after annealing up to ≥600 °C, and necessary conditions for doping by hydrogen are discussed. In (iii), the origin of the commonly observed deep band emission from monocrystalline zinc oxide is investigated using a concept of annealing as-grown samples in different atmospheres. A strong influence by the atmosphere and temperature is observed and the results can be interpreted in terms of dominant effects on the emission by vacancy-related defects.
|
|
| 8. |
- Wang, JH, et al.
(author)
-
Microstructure of Ni-based self-fluxing alloy coating (Part I)
- 2005
-
In: Journal of Iron and Steel Research International. - Amsterdam : Elsevier Science B.V. - 1006-706X .- 2210-3988. ; 12:1, s. 50-53
-
Journal article (peer-reviewed)abstract
- The microstructure of a Ni-based self-fluxing alloy coating produced by an oxygen-acetylene flame spraying Ni-16. 5Cr-3. 3B-4. 7Si-4. 4Fe-0.8C system alloy powder onto a common steel substrate was investigated by microanalysis methods. The phases in the coating were observed by SEM and determined by XEDS X-Ray energy spectrum and X Ray diffraction patterns. Meanwhile, some molecular formulas were calculated.
|
|
| 9. |
- Willander, Magnus, 1948, et al.
(author)
-
High-Temperature Electronic Materials: Silicon Carbide and Diamond
- 2007
-
In: Springer Handbooks. - Boston, MA : Springer US. ; , s. 537-563
-
Book chapter (other academic/artistic)abstract
- The physical and chemical properties of wide-band-gap semiconductors make these materials an ideal wide bandgapsemiconductor choice for device fabrication for applications in many different areas, e.g. light emitters, high-temperature and high-power electronics, high-power microwave devices, micro-electromechanical system (MEM) technology, and substrates for semiconductor preparation. These semiconductors have micro-electromechanical system (MEMS) been recognized for several decades as being suitable for these applications, but until recently the low material quality has not allowed the fabrication of high-quality devices. In this material quality chapter, we review the wide-band-gap semiconductors, silicon carbide and diamond. Silicon carbide electronics is advancing from the research stage to commercial production. The commercial availability of single-crystal SiC substrates during the early 1990s gave rise to intense activity in the development of silicon carbide devices. The commercialization started with the release of blue light-emitting diode (LED). The recent release of high-power Schottky diodes was a further demonstration of the progress made towards defect-free SiC substrates. Diamond has superior physical and chemical properties. Silicon-carbide- and diamond-based diamondsilicon carbide (SiC) electronics are at different stages of development. The preparation of high-quality single-crystal substrates of wafer size has allowed recent significant progress in the fabrication of several types of devices, and the development has reached many important milestones. However, high-temperature studies are still scarce, and diamond-based electronics is still in its infancy.
|
|
| 10. |
- Willander, Magnus, 1948-, et al.
(author)
-
Silicon carbide and diamond for high temperature device applications
- 2006
-
In: Journal of materials science. Materials in electronics. - : Springer Science and Business Media LLC. - 0957-4522 .- 1573-482X. ; 17:1
-
Journal article (peer-reviewed)abstract
- The physical and chemical properties of wide bandgap semiconductors silicon carbide and diamond make these materials an ideal choice for device fabrication for applications in many different areas, e.g. light emitters, high temperature and high power electronics, high power microwave devices, micro-electromechanical system (MEMS) technology, and substrates. These semiconductors have been recognized for several decades as being suitable for these applications, but until recently the low material quality has not allowed the fabrication of high quality devices. Silicon carbide and diamond based electronics are at different stages of their development. An overview of the status of silicon carbide's and diamond's application for high temperature electronics is presented. Silicon carbide electronics is advancing from the research stage to commercial production. The most suitable and established SiC polytype for high temperature power electronics is the hexagonal 4H polytype. The main advantages related to material properties are: its wide bandgap, high electric field strength and high thermal conductivity. Almost all different types of electronic devices have been successfully fabricated and characterized. The most promising devices for high temperature applications are pn-diodes, junction field effect transistors and thyristors. MOSFET is another important candidate, but is still under development due to some hidden problems causing low channel mobility. For microwave applications, 4H-SiC is competing with Si and GaAs for frequency below 10 GHz and for systems requiring cooling like power amplifiers. The unavailability of high quality defect and dislocation free SiC substrates has been slowing down the pace of transition from research and development to production of SiC devices, but recently new method for growth of ultrahigh quality SiC, which could promote the development of high power devices, was reported. Diamond is the superior material for high power and high temperature electronics. Fabrication of diamond electronic devices has reached important results, but high temperature data are still scarce. PN-junctions have been formed and investigated up to 400 °C. Schottky diodes operating up to 1000 °C have been fabricated. BJTs have been fabricated functioning in the dc mode up to 200 °C. The largest advance, concerning development of devices for RF application, has been done in fabrication of different types of FETs. For FETs with gate length 0.2 μm frequencies fT = 24.6 GHz, fmax(MAG) = 63 GHz and fmax(U) = 80 GHz were reported. Further, capacitors and switches, working up to 450 °C and 650 °C, respectively, have also been fabricated. Low resistant thermostable resistors have been investigated up to 800 °C. Temperature dependence of field emission from diamond films has been measured up to 950 °C. However, the diamond based electronics is still regarded to be in its infancy. The prerequisite for a successful application of diamond for the fabrication of electronic devices is availability of wafer diamond, i.e. large area, high quality, inexpensive, diamond single crystal substrates. A step forward in this direction has been made recently. Diamond films grown on multilayer substrate Ir/YSZ/Si(001) having qualities close those of homoepitaxial diamond have been reported recently. © Springer Science + Business Media, Inc. 2006.
|
|
