Characterization of V-defects in InGaN Single Quantum Well Films at the Nanometer Level by High-Spatial-Resolution Cathodoluminescence Spectroscopy

Abstract

We have developed a new scanning electron microscope (SEM) equipped with a Schottky emission (SE) gun that produces a high probe current at an acceleration voltage of less than 5 kV and a cathodoluminescence (CL) spectroscopic system (SE-SEM-CL) equipped with an SE gun and a newly designed parabolic mirror that has a very short working distance of 9 mm in order to enhance the spatial resolution of CL spectroscopy. We have studied CL spectral variations in the vicinity of V-defects in InGaN single quantum well (SQW) film by measuring its CL spectra at the nanometer level, using our SE-SEM-CL system. It has been found that the peak intensity and peak wavelength of the CL peak around 454 nm assigned to the quantum wells emission of the InGaN SQW layer significantly change in the vicinity of the V-defects. We have considered that the change in the peak wavelength is mainly caused by a change in the In content in the InGaN SQW layer. Our SE-SEM-CL has a spatial resolution of less than 40 nm for the InGaN SQW layer.