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通过测量调制掺杂Al0 2 2 Ga0 78N/GaN异质结样品的变频电容 电压 (C V)特性 ,对Al0 2 2 Ga0 78N势垒层表面态的性质进行了研究 .结果发现在小偏压下 ,样品的电容随着测量信号频率的增加而下降 ,说明势垒层中存在表面态 .实验数据分析表明 :表面态密度约为 10 13 cm-2 量级 ,表面态的时间常数比势垒层中其他局域态大 .随着空间隔离层厚度的增加 ,势垒层中其他局域态密度随之增加 .在金属电极和Al0 2 2 Ga0 78N势垒层之间加入Si3 N4绝缘层可以对表面态起到显著的钝化作用 ,使表面态密度降为～ 10 12 cm-2 量级
The properties of the surface state of the Al0 2 2 Ga0 78N barrier layer were studied by measuring the CV characteristics of the Al0 2 2 Ga0 78N / GaN heterojunction samples. It was found that under the low bias voltage, The capacitance of the sample decreases with the increase of the frequency of the measurement signal, indicating that there is a surface state in the barrier layer.Experimental data analysis shows that the surface state density is on the order of 10 13 cm-2 and the time constant of the surface state is lower than that in the barrier layer And other local states are large.With the increase of the thickness of the spacer layer, the density of other local states in the barrier layer increases.Adding Si3N4 insulating layer between the metal electrode and the Al0 2 2 Ga0 78N barrier layer can increase the surface area State played a significant passivation effect, the surface state density decreased to ~ 10 12 cm-2 order of magnitude