THRESHOLD TRAP DENSITY FOR VALID MOTT-SCHOTTKY ANALYSIS IN CARRIER SELECTIVE OPTOELECTRONIC DEVICES

摘要

Solution processed carrier selective devices for optoelectronic applications have gained a lot of recent research interest. Performance optimization of such devices requires detailed understanding of device and material characterization techniques. Capacitance voltage technique using Mott-Schottky (MS) analysis is one such powerful characterization scheme. However, applicability of such analysis for carrier selective PIN devices is not well explained. Here, we report detailed numerical simulations to understand the effect of defect states on CV characteristics. We find that MS analysis is reliable only if trap density is more than a certain threshold trap density, which decreases with thickness of active layer. Apparent linearity in 1/C~2 - V plot is often not sufficient, and hence MS analysis should use devices with different active layer thickness to obtain a reliable estimate of trap densities.