Growth and characterization of Cd_(1-x)Zn_xTe/ZnO heterostructures from furnace-annealed CdTe/Zn multi-stacks

摘要

Cd_(1-x)Zn_xTe/ZnO hetero-structures were grown on glass substrates by furnace annealing of stack-deposited CdTe/Zn/CdTe/Zn thin film multi-layers in air. The multilayered structures were annealed in furnace at various temperatures in between 350 and 600 ℃ XRD results revealed that while growth of Cd_(1-x)Zn_xTe compound reached saturation by 500 ℃, ZnO growth geared up in between 550 and 600 ℃ The band-gap values of the composite structures were less than either standard Cd_(1-x)Zn_xTe or ZnO. It was because of large presence of free Zn and Cd and staggered type-Ⅱ band alignment. An exponential growth was observed for the Cd_(1-x)Zn_xTe particle sizes against annealing temperature. Next SEM images showed reduced surface granularity with increasing Zn percentage in Cd_(1-x)Zn_xTe. SEM micrographs further revealed growth of fiber like formations of ZnO on film surface with increasing annealing temperature. ImageJ software was further used to analyse the SEM micrographs and compositional characteristics from EDX results were co-related with structural, optical and morphological results.