Effect of <i>in situ</i> CdCl2 treatment on spray deposited CdTe∕CdS heterostructure

CdTe thin films have been deposited without and with in situ CdCl2 treatment using spray pyrolysis technique. Scanning electron microscopy studies show enhanced grain growth in the presence of CdCl2. Glancing incidence angle x-ray diffraction is used to observe the microstructural changes of CdTe∕CdS heterostructure at different depths by changing the incident angle. Spraying of CdCl2 on CdS prior to CdTe deposition promotes S diffusion throughout CdTe film and also Te diffusion into CdS. There is an associated change in the microstress of the CdTe film at different layers. The films without CdCl2 treatment show compressive microstress varying from −98to−158MPa with increasing incident angle. CdCl2 spray during CdTe deposition leads to compressive microstress varying from −98MPa at the interface to −19MPa near the surface and CdCl2 spray prior to CdTe deposition leads to a mildly tensile stress (+20to+40MPa). Photoluminescence spectra for CdTe films with the in situ treatment show a reduction in the band gap due to S diffusion as well as the reduction in the defect band intensity. An in situ CdCl2 treatment results in less surface oxidation compared to ex situ process, as seen from x-ray photoelectron spectroscopy study. A shift of ∼200meV in the Fermi energy towards the valence band is also observed in valence band spectra after the in situ CdCl2 treatment.

Перевод пока недоступен