Imaging Nonradiative Point Defects Buried in Quantum Wells Using Cathodoluminescence

Crystallographic point defects (PDs) can dramatically decrease the efficiency of optoelectronic semiconductor devices, many of which are based on quantum well (QW) heterostructures. However, spatially resolving individual nonradiative PDs buried in such QWs has so far not been demonstrated. Here, using high-resolution cathodoluminescence (CL) and a specific sample design, we spatially resolve, image, and analyze nonradiative PDs in InGaN/GaN QWs at the nanoscale. We identify two different types of PDs by their contrastin behavior with temperature and measure their densities from 10(14) cm(-3) to as high as 10(16) cm(-3). Our CL images clearly illustrate the interplay between PDs and carrier dynamics in the well: increasing PD concentration severely limits carrier diffusion lengths, while a higher carrier density suppresses the nonradiative behavior of PDs. The results in this study are readily interpreted directly from CL images and represent a significant advancement in nanoscale PD analysis.

Automated summary

This study demonstrates the successful spatial resolution and analysis of nonradiative point defects in InGaN/GaN quantum wells using high-resolution cathodoluminescence. The different types of point defects were identified by contrasting behaviors and their densities were measured from 10^14 cm^-3 to as high as 10^16 cm^-3. The results show the interplay between point defects and carrier dynamics, highlighting the impact of point defects on carrier diffusion lengths and nonradiative behaviors.