Growth and characterization of hot-wall epitaxial InGaN films using mixed (Ga plus In) source

A simple mixed-source (metallic gallium and indium) method has been used su ccessfully in a hot-wall epitaxial system to grow high-quality InGaN films on sapphire with GaN buffer layers. The InGaN films exhibit sharp and stron g near-band-edge-emissions, ranging from violet (384 nm) to blue (448 nm), with photoluminescence (PL) peak widths ranging from 12-33 nm at room tempe rature. The influence of the mixed-source In/Ga ratio on the In incorporati on and crystal quality is investigated, and it is found that a relatively l ow In/Ga ratio, 1/4-1/5 in the source or 2-3 in the vapor is desirable for improving the crystal quality and enhancing In incorporation. The PL spectr a are obtained from 10 K to 300 K and the activation energy, deduced from t he thermal quenching of the PL intensity, is about 30.5 meV, suggesting a r ather small compositional fluctuation. PL peaks also exhibit anomalous reds hifts (10-70 K) and blue shifts (80-140 K).