Electrical characterization of as-grown and H plasma treated CdTe epitaxial layers

In the present work deep level transient spectroscopy (DLTS) and high-resolution Laplace DLTS were employed to study the electrical properties of defects in as-grown and H-plasma treated CdTe thin films grown by the molecular beam epitaxy technique. We demonstrate that two dominant deep states in as-grown CdTe have the activation energy close to the midgap level and, therefore, could act as recombination centres in these crystals. Both traps are donor-like defects. However, their concentration was found to be too small to influence the electrical properties of devices based on this semiconductor. On the other hand, another dominant midgap trap was observed in H-plasma treated CdTe. The question as to the origin of these defects will be addressed.