Enhanced performance CdZnTe single crystal with few surface damages via solution based annealing

Abstract

In this study, heat treatments were employed using a CdCl2 solution as the annealing medium to investigate the evolution of internal defects and photoelectric properties of CdZnTe crystals. It was observed that CdCl2 crystals formed on the surface of the annealed crystals, and their size increased exponentially with prolonged annealing time. It could be a medium for Cl transport. The liquid-phase annealing process was found to be gentle, resulting in minimal damage and the absence of large defects migrating or accumulating dislocations and less nano-defects on the crystal surface than sample annealed in vapor condition. After a 30 hour annealing, the infrared (IR) transmittance reached 55%, and the resistivity increased to 1.36×1010 Ω·cm. The presence of Cd2+ facilitated the filling of Cd vacancies (VCd) defects through diffusion reduction, while the diffusion of Cl- introduced complex defect with extra VCd, causing the Fermi level to approach the center of the band gap. Consequently, a high-resistance CdZnTe material was achieved.