To enhance energy resolution in semiconductor γ -ray detectors，this study employs ozone-atmosphere KrF excimer laser irradiation on the surface of CdTe single crystals based on the principle of regulating Schottky barrier formation through surface states. This process is found to result in the successful establishment of a Schottky contact at the Au/CdTe interface. I.V characteristic measurements confirmed the transformation of contact type. X-ray photoelectron spectroscopy analysis indicated that laser treatment resulted in the formation of an oxide layer on the surface. This oxide layer effectively passivates surface defects and suppresses leakage current. The laser-modified Au/CdTe/Au Schottky junction detector achieved an energy resolution of 16. 73% for 241Am 59. 5 keV γ -rays， significantly exceeding the 33. 20% resolution of the untreated device.