Controlling metal adatoms on InGaN growing front for defect suppression and high-stability visible-light photodetection

Abstract

Despite the successful commercialization of InGaN-based light emitting diodes, the further application of this material system in photosensitive devices remains hindered by complex crystal defects and lacking understanding of them. Herein, the InGaN epilayers are grown through the synchronous control of In and Ga adatoms on the growing front. Reducing excess In adatoms lowers the surface strain and suppresses the formation of misfit dislocation (MD) networks, while enhancing Ga adatom migration reduces the trench defects as well as the related In-rich hillock regions. Therefore, the nonradiative centers (NRCs) and the localized states played by these surface-visible defects, are both effectively reduced, leading to superior optical performance of the InGaN alloy. Furthermore, optoelectronic characterization using coplanar Schottky-contact photodetectors reveals that the localized states and the deep-level traps associated with these surface defects cause the persistent photoconductive (PPC) effect, resulting in unstable and slow photo-response. Therefore, the suppression of these complex defects contributes to the realization of high-performance InGaN visible-light photodetectors (VLPDs) with high speed and high-temperature stability, exhibiting great potential in wide visible-light applications.