Mg掺杂对AlGaN薄膜特性的影响

Effect of Mg doping on properties of AlGaN films

利用高精度x射线衍射和拉曼散射光谱 ,对MOCVD生长的不同Mg掺杂量的AlGaN薄膜的c轴晶格常数、摇摆曲线和拉曼频移进行测量发现 :当Mg掺杂剂量较小时 ,E2 模式向低频方向漂移表明张力应力有所增加 ,但是摇摆曲线和A1 (LO)模式半高宽减小表明薄膜质量有所提高 ;随着Mg掺杂剂量的增加 ,E2 模式反向漂移表明此时薄膜中存在压力应力 ,同时薄膜质量有所下降 .最后根据拉曼频移和应力改变进行拟合得出相应的线性表达式为Δσ=- 0 2 98+0 5 6 2·ΔE .

Effect of Mg doping on the properties of AlGaN layers grown on sapphire substrates by metal_organic chemical vapor deposition were studied using x_ray diffraction and Raman scattering. When the doping of Mg was low, the E_(2) mode shifted to lower frequency and the full width half at maximum of the rocking curve and A_(1)(LO) mode decreased. However, as the flow rate of CP_(2)Mg increased till the AlGaN was doped with a dose as high as 4×10^(20)cm^(-3), the quality of film decreased gradually and the E_(2) mode shifted to higher frequency, indicating a compressive stress in the films. Finally, the relation between the Raman shift and the stress alteration was described by Δσ=-0.298+0.562ΔE.