GaN homoepitaxy on freestanding (1(1)over-bar00) oriented GaN substrates

We report homoepitaxial GaN growth on freestanding (1 (1) over bar 00) oriented (M-plane GaN) substrates using low-pressure metalorganic chemical vapor deposition. Scanning electron microscopy, atomic-force microscopy, and photoluminescence were used to study the influence of growth conditions such as the V/III molar ratio and temperature on the surface morphology and optical properties of the epilayers. Optimized growth conditions led to high quality (1 (1) over bar 00) oriented GaN epilayers with a smooth surface morphology and strong band-edge emission. These layers also exhibited strong room temperature stimulated emission under high intensity pulsed optical pumping. Since for III-N materials the (1 (1) over bar 00) crystal orientation is free from piezoelectric or spontaneous polarization electric fields, our work forms the basis for developing high performance III-N optoelectronic devices. (C) 2002 American Institute of Physics.