MOVPE growth of thick CdTe heteroepitaxial layers for X‐ray imaging detectors

Abstract

PACS 78.55.Et, 81.05.Dz, 81.15.Gh, 85.60 .GzThe heteroepitaxial growth and characteristics of thick CdTe layers of thickness up to 200 µm grown on GaAs substrates in an atmospheric pressure MOVPE growth system are reported. The X-ray double crystal rocking curve analysis showed the crystalline quality of the epitaxial layers was high, the full width at half maximum values of the CdTe (400) diffraction peaks was around 50-70 arcsec for the layers thicker than 30 µm. Photoluminescence measurements at 4.2 K showed high-intensity bound excitonic emissions and very small defect related peaks indicating their superior structural properties. Surface morphology of the layers was highly dependent on the growth process, and was improved by adopting a two-step growth technique, where a buffer layer was grown first at a low substrate temperature followed by the usual high temperature growth.