A band edge model in （101）-biaxial strained Si on relaxed Si1-x Gex alloy,or monoclinic Si （m-Si）,is presented using the k · p perturbation method coupled with deformation potential theory. Results show that ...
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A band edge model in （101）-biaxial strained Si on relaxed Si1-x Gex alloy,or monoclinic Si （m-Si）,is presented using the k · p perturbation method coupled with deformation potential theory. Results show that the [001], [001], [100], [100] valleys constitute the conduction band （CB） edge,which moves up in electron energy as the Ge fraction （x） increases. Furthermore,the CB splitting energy is in direct proportion to x and all the valence band （VB） edges move up in electron energy as x increases. In addition, the decrease in the indirect bandgap and the increase in the VB edge splitting energy as x increases are found. The quantitative data from the models supply valuable references for the design of the devices.
This paper presents a new power generation structure that can provide DC energy for passive UHF RFID with high sensitivity and high efficiency. The structure is designed with 0.18μm standard CMOS technology, includin...
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This paper presents a new power generation structure that can provide DC energy for passive UHF RFID with high sensitivity and high efficiency. The structure is designed with 0.18μm standard CMOS technology, including two charge pumps,a current reference, and a group of bias circuits. Low-voltage performance is improved thanks to the bias structure,which eliminates the threshold voltage drop and body-effect of conventional circuits. A 350mV minimum input level is required to generate a 1.5V power supply for a 100k~ load with power conversion efficiency （PCE） of 22%. PCE up to 29.8% is achieved with a 60kΩ load. Simulation results show that the new circuit is superior to conventional charge pumps.
Ohmic contacts of Ti/Al/Ni/Au multi-layer metal on A10.27 Ga0.73N/GaN heterostructures were fabricated. Specific contact resistivities were measured by the linear transmission line method （LTLM） and the circular tra...
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Ohmic contacts of Ti/Al/Ni/Au multi-layer metal on A10.27 Ga0.73N/GaN heterostructures were fabricated. Specific contact resistivities were measured by the linear transmission line method （LTLM） and the circular transmission line method （CTLM） ,respectively. A minimum specific contact resistivity of 1.46× 10 ^-5Ω· cm^2z was obtained by evaporating a Ti（10nm）/Al（100nm）/Ni（40nm）/Au（100nm） multi-layer and annealing for 30s at 650℃ in ultra-high purity N2 ambient. A10.27 Ga0.73 N/GaN photoconductor ultraviolet （UV） photodetectors were prepared. The dark current-voltage （I-V） characteristics of the detectors were measured and the result shows that the I- V curve was linear. Experimental results indicate that good ohmic contact on the Al0.27 Ga0.73 N/GaN heterostructure is obtained and it can be applied in high- performance AlGaN/GaN UV photodetector fabrications.
A model is presented to describe a compensation mechanism for semi-insulating 6H-SiC grown with the intentional doping of vanadium. Because we found nitrogen to be the principal shallow donor impurity in SiC by second...
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A model is presented to describe a compensation mechanism for semi-insulating 6H-SiC grown with the intentional doping of vanadium. Because we found nitrogen to be the principal shallow donor impurity in SiC by secondary ion mass spectroscopy （SIMS） measurements, semi-insulating properties in SiC are achieved by compensating the nitrogen donor with the vanadium deep acceptor level. The presence of different vanadium charge states V^3＋ and V^4＋ is detected by electron paramagnetic resonance and optical absorption measurements,which coincides with the results obtained by SIMS measurements. Both optical absorption and low temperature photoluminescence measurements reveal that the vanadium acceptor level is located at 0.62eV below the conduction band in 6H-SiC.
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