MOCVD growth of InN thin films at different temperatures using pulsed trimethylindium approach

Abstract

The growth of indium nitride (InN) thin films via metalorganic chemical vapor deposition (MOCVD) is often hindered by nitrogen deficiency at lower growth temperatures. To address this limitation, we report on the MOCVD growth of InN thin films at three temperatures (i.e., 570 °C, 585 °C, and 600 °C) using a pulsed trimethylindium (TMIn) approach. This method can achieve an ultra-high effective V/III molar ratio of 120 K, effectively mitigating nitrogen deficiency and promoting high-quality film growth. High-resolution X-ray diffraction (XRD) measurements revealed that wurtzite structure InN thin films were successfully grown. Field emission scanning electron microscopy images showed that the InN exhibits a 3D growth mode, and the island size is proportional to growth temperature. Subsequently, the crystalline quality improved with higher growth temperatures due to reduced coalescence boundaries. From the XRD rocking curve omega-scans, the edge and screw dislocation density magnitude is in the order of × 10¹⁰ cm⁻² and × 10⁸ cm⁻², respectively. As the growth temperature increased, the bandgap energy was redshifted from 0.92 eV to 0.87 eV; while Hall mobility was reduced from 149 cm²/Vs to 130 cm²/Vs. The results revealed that higher growth temperature tends to produce InN with better crystal quality and optical properties. In addition, the results also lead to the conclusion that the ultra-high effective V/III ratio of the pulsed TMIn approach is promising and could minimize the nitrogen deficiency nature of low-temperature MOCVD growth.