| 1. |
- Araujo, C. M., et al.
(författare)
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Electrical resistivity, MNM transition and band-gap narrowing of cubic GaN : Si
- 2002
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Ingår i: Microelectronics Journal. - 0026-2692. ; 33:4, s. 365-369
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Tidskriftsartikel (refereegranskat)abstract
- The electrical resistivity of the Si-donor cubic GaN is investigated theoretically at low temperature. The critical impurity concentration, N-c, for the metal-nonmetal transition is estimated in three different ways: from using the generalized Drude approach (GDA) for the resistivity; from the vanishing of the chemical potential calculated using the dielectric function model with a Lorentz-Lorenz correction; from finding the crossing point between the energy in the insulating and metallic states. The bandgap narrowing (BGN) has been determined theoretically and experimentally above the MNM transition, The experimental data have been obtained with photoluminescence measurements. Theoretical and experimental results are in rough agreement in the range of impurity concentration of interest.
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| 2. |
- Iwata, H., et al.
(författare)
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A new type of quantum wells : Stacking faults in silicon carbide
- 2003
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Ingår i: Microelectronics Journal. - 0026-2692. ; 34:5, s. 371-374
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We report on a new type of quantum wells with the width as thin as 10Å, which are composed of SiC only, and consequently have ideal interfaces. These quantum wells are actually stacking faults in SiC. Certain types of stacking faults in SiC polytypes create small 3C-like regions, where the stacking sequences along the c-axis become locally cubic in the hexagonal host crystals. Since the conduction band offsets between the cubic and hexagonal polytypes are very large with the conduction band minima of 3C-SiC lower than that of the other polytypes, such thin 3C inclusions can introduce locally lower conduction bands, thus acting as quantum films perpendicular to the c-axis. One mechanism for the occurrence of stacking faults in the perfect SiC single crystals is the motion of partial dislocations in the basal planes, the partial dislocations leaving behind stacking fault regions. © 2003 Elsevier Science Ltd. All rights reserved.
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| 3. |
- Andersson, Henrik, et al.
(författare)
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System of nano-silver inkjet printed memory cards and PC card reader and programmer
- 2011
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Ingår i: Microelectronics Journal. - : Elsevier BV. - 0959-8324 .- 0026-2692. ; 42:1, s. 21-27
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Tidskriftsartikel (refereegranskat)abstract
- This work describes the development of inkjet printed, low-cost memory cards, and complementary pair of memory card reader and card reader/programmer for PCs. This constitutes a complete system that can be used for various applications. The memory cards are manufactured by inkjet printing nano-silver ink on photo paper substrate. The printed memory structures have an initial high resistance that can later be programmed to specific values representing data on the cards, the so called Write Once Read Many (WORM) memories. The memory card reader measures the resistance values of the memory cells and reads it back to the computer by USB connection. Using multiple resistance levels that represent different states it is possible to have a larger number of selectable combinations with fewer physical bits compared to binary coding. This somewhat counters one of the limitations of resistive memory technology that basically each cell needs one physical contact. The number of possible states is related to the resolution of the reader and the stability of the WORM memory.
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| 4. |
- Andersson, Thorvald, 1946, et al.
(författare)
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Macroscopic defects in GaN/AlN multiple quantum well structures grown by MBE on GaN templates
- 2009
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Ingår i: Microelectronics Journal. - : Elsevier BV. - 0026-2692. ; 40:2, s. 360-362
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Tidskriftsartikel (refereegranskat)abstract
- We have used MBE to grow in AlN/GaN superlattices, with different number of periods, on 2.5-mu m-thick MOVPE-GaN templates to study the development of defects such as surface deformation due to strain. After growth the samples were studied by atomic force microscopy (AFM), transmission electron microscopy (TEM), XRD and Fourier transform infrared spectroscopy (FT-IR). The strain increased with the number of quantum wells (QWs) and eventually caused defects such as microcracks visible by optical microscopy at four or more QW periods. High-resolution TEM images showed shallow recessions on the surface (surface deformation) indicating formation of microcracks in the MQW region. The measured intersubband (IS) absorption linewidth from a four period structure was 97 meV, which is comparable with the spectrum from a 10 period structure at an absorption energy of similar to 700 meV. This indicates that the interface quality of the MQW is not substantially affected by the presence of cracks.
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| 5. |
- Baroni, Mpma, et al.
(författare)
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Modeling and gradient pattern analysis of irregular SFM structures of porous silicon
- 2006
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Ingår i: Microelectronics Journal. - : Elsevier BV. - 0026-2692. ; 37:4, s. 290-294
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Tidskriftsartikel (refereegranskat)abstract
- Technological applications in opto-electronic devices have increased the interest in characterizing porous silicon structure patterns. Due to its physical properties, solutions from KPZ 2D are adopted to simulate the structure of porous material interface whose spatial characteristics are equivalent to those found in porous silicon samples. The analysis of the simulated and real scanning Force Microscopy (SFM) surfaces was done using the Gradient Pattern Analysis (GPA). We found that the KPZ 2D model presented asymmetry levels compatible with the irregular surfaces observed by means of SFM images of pi-Si.
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| 6. |
- Chouhan, Shailesh, et al.
(författare)
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A 352nW, 30 ppm/°C all MOS nano ampere current reference circuit
- 2017
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Ingår i: Microelectronics Journal. - : Elsevier. - 0959-8324 .- 0026-2692. ; 69, s. 45-52
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Tidskriftsartikel (refereegranskat)abstract
- In this work, an ultra low power all-MOSFET based current reference circuit, developed in 0.18 µm CMOS technology, is presented. The proposed circuit is based on the classical resistor-less beta multiplier circuit with an additional temperature compensation feature. The circuit is capable of providing the reference current in a nanoampere range for the supply voltage ranging from 1 V to 2 V in the industrial temperature range of −40 °C to 85 °C. The measurements were performed on 10 prototypes. The measured mean value of the reference current is 58.7 nA with a mean temperature coefficient value of 30 ppm/°C. In addition, the measured mean line regulation is 3.4%/V in the given supply voltage range. The total current consumption of the circuit is 352 nA and the chip area is 0.036 mm2.
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| 7. |
- Holtz, Per-Olof, 1951-, et al.
(författare)
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Effects of External Fields on the Excitonic Emission from Single InAs/GaAs Quantum Dots
- 2008
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Ingår i: Microelectronics Journal, Vol. 39. - Microelectronics Journal : Elsevier. ; , s. 331-334
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Konferensbidrag (refereegranskat)abstract
- A low-temperature micro-photoluminescence (μ-PL) investigation of InAs/GaAs quantum dots (QDs) exposed to a lateral external electric field is reported. It is demonstrated that the QDs PL signal could be increased several times by altering the external and/or the internal electric field. The internal field in the vicinity of the dots could be altered by means of an additional infra-red laser. We propose a model, which is based on an essentially faster lateral transport of the charge carriers achieved in an external electric field. Consequently, also the capture probability into the dots and subsequently the dot luminescence is also enhanced. The results obtained suggest that the lateral electric fields play a major role for the dot luminescence intensity measured in our experiment.
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| 8. |
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| 9. |
- Jalili, Armin, et al.
(författare)
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Inter-channel offset and gain mismatch correction for time-interleaved pipelined ADCs
- 2011
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Ingår i: Microelectronics Journal. - Oxford, UK : Elsevier. - 0959-8324 .- 0026-2692. ; 42:1, s. 158-164
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a digital background calibration technique to compensate inter-channel gain and offset errors in parallel, pipelined analog-to-digital converters (ADCs). By using an extra analog path, calibration of each ADC channel is done without imposing any changes on the digitizing structure, i.e., keeping each channel completely intact. The extra analog path is simplified using averaging and chopping concepts, and it is realized in a standard 0.18‐μm CMOS technology. The complexity of the analog part of the proposed calibration system is same for a different number of channels.Simulation results of a behavioral 12-bit, dual channel, pipelined ADC show that offset and gain error tones are improved from −56.5 and −58.3 dB before calibration to about −86.7 and −103 dB after calibration, respectively.
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| 10. |
- Johannesson, Daniel, et al.
(författare)
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Analytical PSpice model for SiC MOSFET based high power modules
- 2016
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Ingår i: Microelectronics Journal. - : Elsevier. - 0026-2692. ; 53, s. 167-176
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Tidskriftsartikel (refereegranskat)abstract
- A simple analytical PSpice model has been developed and verified for a 4H–SiC based MOSFET power module with voltage and current ratings of 1200 V and 120 A. The analytical simulation model is a temperature dependent silicon carbide (SiC) MOSFET model that covers static and dynamic behavior, leakage current and breakdown voltage characteristics. The technology dependent MOSFET modeling parameters are extracted from characterization measurements, datasheets and PSpice simulations at various temperatures. The SiC MOSFET model is implemented in the PSpice circuit simulation platform using PSpice standard components and analog behavior modeling (ABM) blocks. The MOSFET switching performance is investigated under influence of different circuit elements, such as stray inductance, gate resistance and temperature, in order to study and estimate on-state and switching losses pre-requisite for design of various converter and inverter topologies. The performance of the SiC MOSFET model is fairly accurate and correlates well with the measured results over a wide temperature range.
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