肖特基C-V法研究Al_xGa_(1-x)N/GaN异质结界面二维电子气

Investigation on Two-Dimensional Electron Gas in Al_xGa_(1-x) N/GaN Heterostructures by Using Schottky C-V Measurement

通过对 Pt/ Al0 .2 2 Ga0 .78N/ Ga N肖特基二极管的 C- V测量 ,研究分析了 Al0 .2 2 Ga0 .78N/ Ga N异质结界面二维电子气 (2 DEG)浓度及其空间分布 .测量结果表明 ,Al0 .2 2 Ga0 .78N/ Ga N异质结界面 2 DEG浓度峰值对应的深度在界面以下 1.3nm处 ,2 DEG分布峰的半高宽为 2 .3nm ,2 DEG面密度为 6 .5× 10 1 2 cm- 2 .与 Alx Ga1 - x As/ Ga As异质结相比 ,其 2 DEG面密度要高一个数量级 ,而空间分布则要窄一个数量级 .这主要归结于 Alx Ga1 - x N层中～ MV / cm量级的压电极化电场和自发极化电场对 Alx Ga1 - x N/ Ga N异质结能带的调制和 Alx Ga1 - x N/ Ga

Concentration and spatial distribution of the two dimensional electron gas (2DEG) near the Al 0.22 Ga 0.78 N/GaN heterointerface are investigated by using Schottky C V measurement.The peak value of the 2DEG concentration occurs at 1 3nm beneath the heterointerface.The full width at half maximum (FWHM) of the 2DEG peak is 2 3nm and the sheet density of the 2DEG is 6 5×10 12 cm -2 .The sheet density of the 2DEG is one order higher and the FWHM is one order lower than those in Al x Ga 1-x As/GaAs heterostructures,because of the piezoelectrically induced polarization field in the order of ～MV/cm,which will strongly modulate the conduction band of Al x Ga 1-x N/GaN heterostructure,as well as the much larger conduction band discontinuity in the Al x Ga 1-x N/GaN heterointerface.