CdCl₂ activation annealing of CdTe microwires grown by close-spaced sublimation method

We report on the effect of CdCl₂ treatment on CdTe microwires that were grown using a simple close-spaced sublimation method. Au particles were used for catalytic vapor-liquid-solid growth of the CdTe microwires with a direct band-gap of ~1.49 eV. The optical, morphological and structural properties of the CdTe microwires were characterized after post-growth CdCl ₂ treatment at 385°C for 15 ~ 90 min by scanning electron microscopy, X-ray diffraction, μ-Raman scattering, μ-photoluminescence spectroscopy and focused-ion-beam techniques. New grains nucleated at the surface of CdTe microwires were observed after CdCl₂ treatment. The orientations of the CdTe microwires and of the underlying CdTe thin films became more randomized with increasing durations of CdCl₂ treatment. However, the optical properties were hardly affected by CdCl₂ treatment. Post-growth CdCl₂ activation on CdTe microwires is a critical process for high efficiency CdTe microwire-based solar cells.