Universal and scalable route to fabricate GaN nanowire-based LED on amorphous substrate by MOCVD

Abstract

GaN-based light-emitting diodes (LEDs) on sapphire are known to exhibit high efficiency and long lifetime. Currently, Si substrate has been explored for the replacement of sapphire substrate due to the size limitations. In order to fabricate the cost-effective LEDs on larger scale, the most efficient approach is the growth of scalable and high crystal quality GaN nanowires on amorphous substrate, preferably glass. Here, for the first time, we have demonstrated the growth of GaN nanowire-based LEDs using metal-organic chemical vapor deposition (MOCVD) on an amorphous glass substrate. Additionally, the InGaN/GaN multiple quantum well shells are conformally grown on semipolar {112¯2} growth facet of m-axial GaN core nanowires and resulted in reduced quantum confined Stark effect. The optical properties of the nanowire-ensemble are rigorously evaluated by both temperature-dependent and time-resolved photoluminescence (PL), whereas the emission from the single nanowire is examined by spatially resolved cathodoluminescence. The PL spectroscopy of the GaN core nanowire-ensemble reveals a very high crystal quality due to the dominant emission from the band-to-band transition and absence of a characteristic yellow luminescence. Furthermore, the temperature-dependent PL of the nanowire ensemble exhibits a very high internal quantum efficiency of 76.1 %. Therefore, the ultrashort radiative lifetime of the carriers was in the range between 19 ps and 54 ps. These results emphasize the potential of our approach to grow high-crystal quality GaN nanowires on amorphous substrates for large scale production and various optical applications such as LEDs, solar cells, and photodetectors.