Imaging Nonradiative Point Defects Buried in Quantum Wells Using Cathodoluminescence

Abstract

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 contrasting 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.

Surface Recombinations in III-Nitride Micro-LEDs Probed by Photon-Correlation Cathodoluminescence

“…30 Finally, the last option is to enhance the recombination rate. This could be achieved by reducing the QW thickness, 31 increasing the driving current 32 or by using semi-polar or non-polar structures. Additional simulations, showing the impact of these parameters on the IQE, are presented in SI Section III.…”

Diffusion Analysis of Charge Carriers in InGaN/GaN Heterostructures by Microphotoluminescence

“…Additionally, we assume the carrier lifetime to decrease with increasing temperature due to thermal activation of defects, although different studies showed an opposite trend. [ 23,25 ] The dependencies of the effective carrier lifetime on temperature in these studies are small, changing with a factor of about 2. In another study by Nippert et al, the temperature change of the ABC parameter was investigated.…”

Structural, Optical, and Electrical Characterization of 643 nm Red InGaN Multiquantum Wells Grown on Strain‐Relaxed InGaN Templates

“…To examine the optical quality of the MQWs, the IQE is often estimated by first assuming the IQE is 100% at low temperature and referencing the PL efficiency, defined as , at room temperature to the PL efficiency measured at the same laser power density and low temperature (<20 K). However, this assumption is not always valid because there are some nonradiative processes that are active below 20 K. [ 33–35 ] In order to minimize the error from this assumption, the PL efficiency was measured by varying the laser power density and temperature. The IQE was then estimated by normalizing to the maximum PL efficiency measured at 14 K, where the radiative rate dominates over the nonradiative rate, as shown in Figure .…”