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.
Polysilicon ohmic contacts to n-type 4H-SiC have been fabricated. TLM （transfer length method） test patterns with polysilicon structure are formed on n-wells created by phosphorus ion （P^＋） implantation into a Si...
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Polysilicon ohmic contacts to n-type 4H-SiC have been fabricated. TLM （transfer length method） test patterns with polysilicon structure are formed on n-wells created by phosphorus ion （P^＋） implantation into a Si-faced p-type 4H-SiC epilayer. The polysilicon is deposited using low-pressure chemical vapor deposition （LPCVD） and doped by phosphorous ions implantation followed by diffusion to obtain a sheet resistance of 22Ω/□. The specific contact resistance pc of n^＋ polysilicon contact to n-type 4H-SiC as low as 3.82 × 10^-5Ω· cm^2 is achieved. The result for sheet resistance Rsh of the phosphorous ion implanted layers in SiC is about 4.9kΩ/□. The mechanisms for n^＋ polysilicon ohmic contact to n-type SiC are discussed.
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