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采用O2等离子体及HF溶液对AlGaN/GaN异质结材料进行表面处理后,Ni/Au肖特基接触特性比未处理有了明显改善,反向泄漏电流减小3个数量级.对制备的肖特基接触进行200—600℃5min的N2气氛退火,发现退火冷却后肖特基反向泄漏电流随退火温度增大进一步减小.N2气中600℃退火后肖特基二极管C-V特性曲线在不同频率下一致性变好,这表明退火中Ni向材料表面扩散减小了表面陷阱密度;C-V特性曲线随退火温度增大向右移动,从二维电子气耗尽电压绝对值减小反映了肖特基势垒的提高.
After the surface treatment of AlGaN / GaN heterojunction material by O2 plasma and HF solution, the contact characteristics of Ni / Au Schottky have been significantly improved compared with untreated, and the reverse leakage current decreases by 3 orders of magnitude. Te based contact was annealed in N2 atmosphere at 200-600 ℃ for 5min and the Schottky reverse leakage current after annealing was found to decrease further with the increase of annealing temperature.The CV curve of Schottky diode after annealing at 600 ℃ in N2 gas was different The better coincidence at the frequency shows that Ni diffuses to the surface of the material during anneal, reducing the surface trap density. The CV curve shifts to the right as the annealing temperature increases, and the absolute value of the voltage depletion from the two-dimensional electron gas reflects the small Tigabit barriers to improvement.