An evolution on MgI2 activation temperature to CdTe films for solar cells.

The CdCl2 treatment to CdTe absorber layers leads to grain growth, sintering, reorientation, inversion of the grain boundaries, enhancement in carrier concentration and performance of the solar cell devices concerned but, CdCl2 compound is highly toxic and requires more safety procedures which make this treatment expensive. To reduce the toxicity and seek the accessibility of other halides as an activation agent, in the present work, the MgI2 activation is carried out to optimize physical properties of CdTe absorber layers. Thermally evaporated CdTe films having thickness of 600 nm are activated with MgI2 at 235 °C, 310 °C and 385 °C temperatures. The structural study reveals that films are polycrystalline in nature having cubic phase with (310) preferred orientation whose intensity and corresponding crystallite size are enriched from 38 nm to 48 nm with treatment. The optical energy band-gap is varied from 1.46 eV to 1.85 eV with treatment. PL spectra of films reveal two emission peaks centered at ∼652 nm and ∼705 nm due to native defects and extrinsic impurities. [ABSTRACT FROM AUTHOR]