Growth and characterization of InN layers by metal-organic vapour phase epitaxy in a close-coupled showerhead reactor

We report the synthesis of InN via low-pressure metal-organic vapour phase epitaxy (MOVPE) in a close-coupled showerhead reactor system. InN layers were deposited on GaN buffer layers on c-plane sapphire substrates using trimethylindium and ammonia precursors. We have studied the effect of growth temperature, V/III ratio, and reactor pressure, on the structural, optical and electrical properties of InN layer. All the InN layers deposited are highly mosaic, and we have extracted details of the layer tilt, twist, lateral and vertical coherence lengths, and lattice parameter variations by a careful analysis of the high-resolution X-ray diffraction (HRXRD) data, and correlated these with results obtained from photoluminescence (PL) and Hall mobility measurements. We obtain InN with an intrinsic bandgap of ∼0.7 eV whose measured absorption edge is strongly influenced by background carrier concentration. Nitrogen vacancies play key role in determining measured band edge and lattice constants. Optimized growth conditions at 530 °C, V/III ratio of 18,700, and reactor pressure 500 Torr results in layers with carrier concentration ∼1–2×1019 cm−3 and mobility 150–200 cm2/V s.