Depth profiling study of in situ CdCl_2 treated CdTe/CdS heterostructure with glancing angle incidence X-ray diffraction

摘要

CdTe thin films have been deposited using spray pyrolysis technique without and with in situ CdCl_2 treatment. Scanning electron microscopy studies show enhanced grain growth in the presence of CdCl_2. Glancing angle incidence X-ray diffraction is used for the micro structural study of polycrystalline CdS/CdTe heterostructure at different depths by changing the incident angle. Spraying of CdCl_2 on CdS prior to CdTe deposition promotes S diffusion throughout CdTe film and also Te diffusion into CdS. Whereas spraying of CdCl_2 in between CdTe deposition prevents S diffusion partially and Te diffusion completely. There is an associated change in the microstress of the CdTe film at different layers. The films without CdCl_2 treatment show compressive microstress varying from -98 to -158 MPa with increasing incident angle. CdCl_2 spray during CdTe deposition shows compressive microstress, which varies from -98 MPa at the interface to -19 MPa near the surface and CdCl_2 spray prior to CdTe deposition leads to a mildly tensile stress, from + 40 to + 20 MPa, which is very close to the standard shear stress of ～ 10 MPa for CdTe.