Observation of long-range carrier diffusion in InGaN quantum wells, and implications from fundamentals to devices

TL;DR

This study demonstrates that carriers in high-quality InGaN quantum wells can diffuse over tens of microns at room temperature, challenging previous assumptions and impacting device design and interpretation of photoluminescence data.

Contribution

It provides the first detailed measurement and modeling of long-range carrier diffusion in InGaN quantum wells, linking fundamental physics to practical device implications.

Findings

Carriers diffuse up to tens of microns at room temperature.

Diffusion length depends strongly on excitation density.

The diffusion behavior is explained by a comprehensive recombination model.

Abstract

Photoluminescence measurements on high-quality InGaN quantum wells reveal that carriers diffuse laterally to long distances at room temperature, up to tens of microns. This behavior, which shows a pronounced dependence on the excitation density, contrasts with the common expectation of a short diffusion length. The data is well explained by a diffusion model taking into account the full carrier recombination dynamics, obtained from time-resolved measurements. These observations have important implications for understanding the high efficiency of III-nitride emitters, but also to properly interpret photoluminescence experiments and to design efficient small-scale devices.