MOVPE-grown n-InxGa1-xN (x~0.5)/p-Si(111) template as a novel substrate

This paper proposes for the first time the preparation of n-InGaN/p-Si templates as substrates for InGaN device applications. By using MOVPE, a thick (~0.5 m) InGaN with an intermediate In composition has been successfully grown on Si(111) substrates using an AlN interlayer. By optimizing growth temperature and TMI/(TMI+TEG) molar ratio, InGaN films with In content up to 0.5 are successfully grown. Tensile stress in InGaN films grown at 700°C is estimated to be about half of that for GaN grown at 1100°C and no cracks are found in the InGaN layers. The films grown at a relatively high temperature (700-750°C) show phase separation when their thickness exceeds a critical value. Critical thickness for phase separation is larger for a film grown at a lower temperature with a high In content. For InGaN grown at 600°C with a thickness of 0.8 m, no phase separation is detected by both X-ray diffraction and PL. Such a low temperature-grown InGaN shows a large tilt fluctuation. Ohmic I-V characteristics are obtained between n-InGaN and p-Si and the resistance is markedly decreased with increasing In content in InGaN. The Si pn junction beneath the In0.42Ga0.58N layer behaves well as a solar cell with an InGaN filter. For both n-InGaN/p-Si, the presence of an AlN interlayer between the epilayer and the substrate does not have a significant contribution to the series resistance.