Trap Density Assessment on Multilayer WS2 using Power-Dependent Indirect Photoluminescence

Abstract

Material or interface defectivity assessment of 2D materials remains a challenge, specifically in terms of simple techniques which can be integrated in a CMOS process line. Here we demonstrate an optical technique that assesses interface trap densities, based on the indirect photoluminescence emission. We achieved that by demonstrating the modulation of the indirect/direct photoluminescence peak intensity ratio by the exciton concentration and then linking the modulation to the trap-sensitive non-radiative Auger recombination. Calibration is achieved through theoretical modeling of the recombination mechanisms and, as an example of the methodology, a trap density between 1.6 × 1010 cm−2 and 1.2 × 1011 cm−2 is extracted from (hBN/)WS2/SiO2 structures.