Understanding peculiarities in the optoelectronic characteristics of light emitting diodes based on (In,Ga)N/GaN nanowires

TL;DR

This study compares the optoelectronic performance of (In,Ga)N/GaN nanowire LEDs with Ni/Au and ITO top contacts, demonstrating that ITO significantly enhances emission efficiency, reduces turn-on voltage, and improves overall device performance.

Contribution

It reveals that replacing Ni/Au with ITO as the p-type top contact markedly improves the efficiency and electrical characteristics of nanowire-based LEDs.

Findings

ITO contact increases electroluminescence emission density by ten times

Devices with ITO show lower turn-on voltage and series resistance

External quantum efficiency improves by over an order of magnitude with ITO

Abstract

We investigate the effect of the p-type top contact on the optoelectronic characteristics of light emitting diodes (LEDs) based on (In,Ga)N/GaN nanowire (NW) ensembles grown by molecular beam epitaxy on Si substrates. We compare devices fabricated with either Ni/Au or indium tin oxide (ITO) top contact. The NW-LEDs with ITO exhibit a number density of NWs emitting electroluminescence about ten times higher, significantly lower turn-on voltage and series resistance, and a relative external quantum efficiency more than one order of magnitude higher than the sample with Ni/Au. These results show that limitations in the performance of such devices reported so far can be overcome by improving the p-type top-contact.