Growth and characterization of Cu2ZnSn(Sx Se1−x)4 single crystal grown by traveling heater method

Abstract

High-quality Cu2ZnSn(SxSe1−x)4 (CZTSxSe1−x) single crystals were grown by the traveling heater method (THM), which is an example of a solution growth process. The CZTSxSe1−x solute–Sn solvent pseudobinary system was investigated and the ranges of growth temperature and quantity of solvent were determined for THM growth. The CZTSxSe1−x single crystals were obtained from a 70–80mol% CZTSxSe1−x solution at growth temperature 900°C and speed 4–5mm/day. The structural and compositional analyses of the grown single crystals were carried out by powder X-ray diffraction, Raman spectroscopy and electron probe microanalysis. The grown crystals were kesterite and nearly stoichiometric with slightly Cu-poor and Zn-rich despite the excess Sn used as the solvent. As the sulfur content x increases, the carrier concentration increases slightly but systematically between 2×1017 and 3×1017cm−3 while the mobility decreases from 35.1 to 10.4cm2V−1s−1. These data provide references for the results of characterization on thin film samples as well as giving insight into the defect equilibrium and resulting quantities such as doping and mobility affecting device performance.