Nucleation and islands growth of CdZnTe(0 0 1) epitaxial films on GaAs(0 0 1) substrates by close spaced sublimation

Publication date: 15 September 2018
Source:Journal of Crystal Growth, Volume 498
Author(s): Kun Cao, Wanqi Jie, Gangqiang Zha, Tingting Tan, Yingrui Li, Ruiqi Hu
The early stages of close spaced sublimation growth of CdZnTe(0 0 1)/GaAs(0 0 1) epilayer were experimentally studied under different substrate temperatures and ambient pressures. SEM, AFM, XRD, EBSD and EDS were used for the characterization of morphology, structure and composition of the films. The films were found to be (0 0 1) oriented and epitaxial in nature with zinc blende cubic structure. Deposition models were used to explain the correlation between growth condition and CdZnTe island morphology. Films grown at 350 °C and 1 × 10² Pa show the best uniform and smooth surface. When increasing substrate temperature to 430 °C or ambient pressure to 1 × 10⁴ Pa or 3 × 10⁴ Pa, islands are less compact and exhibit preferential growth along one of 〈1 1 0〉 directions, which could be resulted from the big lattice mismatch (14.0%) of Cd0.9Zn0.1Te(0 0 1)/GaAs(0 0 1) heterojunction. For the growth at 430 °C in 3 × 10⁴ Pa, prior nucleation at defect site was found, and the appearance of regular 〈0 1 0〉 oriented island edges proposes that steps 〈0 1 0〉{1 0 0} are more stable for CdZnTe(0 0 1)/GaAs(0 0 1) epilayer than steps 〈1 1 0〉{1 1 1}.