Unstrained InAlN/GaN heterostructures grown on sapphire substrates by MOCVD

Abstract

InAlN/GaN heterostructures were grown on sapphire substrates by low-pressure metal organic chemical vapor deposition. The influences of NH3 flux and growth temperature on the In composition and morphologies of the InAlN were investigated by X-ray diffraction and atomic force microscopy. It's found that the In composition increases quickly with NH3 flux decrease. But it's not sensitive to NH3 flux under higher flux. This suggests that lower NH3 flux induces a higher growth rate and an enhanced In incorporation. The In composition also increases with the growth temperatures decreasing, and the defects of the InAlN have close relation with In composition. Unstrained InAlN with In composition of 17% is obtained at NH3 flux of 500 sccm and growth temperature of 790 °C. The InAlN/GaN heterostructure high electron mobility transistor sample showed a high two-dimensional electron gas (2DEG) mobility of 1210 cm2/(V·s) with the sheet density of 2.3 × 1013 cm−2 at room temperature.