InGaN/GaN多量子阱的组分确定和晶格常数计算

Determination of chemical composition and average crystal lattice constants of InGaN/GaN multiple quantum wells

采用金属有机化学气相沉积(MOCVD)技术以蓝宝石为衬底在n型GaN单晶层上生长了InGaN/GaN多量子阱结构外延薄膜,利用高分辨X射线衍射(HRXRD),卢瑟福背散射/沟道(RBS/channeling),以及光致发光(PL)技术对InGaN/GaN多量子阱结构薄膜分别进行了平均晶格常数计算、In原子替位率计算和In组分的定量分析.研究表明:InGaN/GaN多量子阱的水平和垂直方向平均晶格常数分别为aepi=0.3195nm,cepi=0.5198nm,In原子的替位率为99.3%,利用HRXRD和RBS/channeling两种分析技术计算In的组分分别是0.023和0.026,并与样品生长时设定的预期目标相符合,验证了两种实验方法的准确性;而用室温条件下的光致发光谱(PL)来计算InGaN/GaN多量子阱中In的组分是与HRXRD和RBS/channeling的实验结果相差很大,说明用PL测试In组分的方法是不适宜的.

The samples of InGaN/GaN muhiple quantum wells （MQWs） have been grown on （0001） sapphire substrate with n-GaN buffer layer by metal-organic chemical vapor deposition （ MOCVD）. According to the results of Rutherford backscattering （RBS）/ channeling along （0001） axis, the conventional θ-2θ scans normal to GaN （0004） and （10 14） plane at 0° and 180° azimuth angles and the photoluminescenee （PL） properties at room temperature, we concluded that In atoms in the InGaN/GaN MQWs are highly substituted, with the substitution rate over 99%, and the average crystal lattice constants of InGaN/GaN MQWs were calculated accurately （ aepi = 0.3195 nm, cepi = 0.5198 nm）, which are almost equal to theoretical data. Using HRXRD and RBS,the atomic content of In was determined to be respectively 0.023 and 0.026, the result was consistent with actual growth conditions of InGaN/GaN MQWs. However, there was a great difference compared with In chemical composition obtained by PL properties, which shows that PL properties are not suitable for measuring the In chemical composition in InGaN/GaN MQWs.