表面钝化前后Al0.22Ga0.78N/GaN异质结势垒层应变的高温特性

用高分辨X射线衍射仪(HRXRD)研究了表面钝化前后Al_0.22Ga_0.78N/ GaN异质结势垒层应变的高温特性，温度变化范围从室温到813K.结果表明，对未钝化的异质 结，当测试温度高于523K时，Al_0.22Ga_0.78N势垒层开始出现应变 弛豫；钝化后，在Al_0.22Ga_0.78N势垒层中会产生一个附加的平面 拉伸应变，并随着温度的增加，势垒层中的平面拉伸应变会呈现出一个初始的增加，接着应 变将减小，对100nm厚的Al_0.22Ga_0.78N势垒层，应变只是轻微地减 小，但对于50nm厚的Al_0.22Ga_0.78N势垒层，则出现了严重的应变 弛豫现象.关键词：0.22Ga_0.78N/GaN异质结')" href="#">Al_0.22Ga_0.78N/GaN异质结应变3 N₄钝化')" href="#">Si₃ N₄钝化高温XRD

The effects of passivation and temperature on the barrier strain of Al0.22Ga0.78N/GaN heterostructures

The barrier strain in Al0.22 Ga0.78 N/GaN heterostrueture, with and without Si3N4 passivation layer, was investigated at temperatures from room temperature to 813K by using high resolution X-ray diffraction. The strain relaxation occurs when the temperature exceeds 523K for the unpassivated Al0.22 Ga0.78 N layers. After passivation, an initial increase of the strain with increasing temperature is observed in Al0.22 Ga0.78 N layers, and at the higher temperatures the strain only decreases slightly in the 100-nm-thick Al0.22Ga0.78 N layer, but a pronounced strain relaxation occurs in the 50-nm-thick one due to the fact that the thickness of the Al0.22 Ga0.78 N layer is close to the critical thickness, and hence the increase of tensile strain induced by passivation will result in partial strain relaxation via the formation of cracks or the gliding motion and multiplication of dislocations.