In/CdTe/Au p-n Gamma-ray Detectors Fabricated Using n-type Layer Formed by Laser-induced Back-side Doping with Nd:YAG Laser

An n-type layer was formed in p-type CdTe via the laser-induced back-side doping of In with a Nd:YAG laser. Hall effect measurements confirmed the formation of an n-type layer on the In-doped area. The In/CdTe/Au p-n diode was fabricated as a gamma-ray detector via laser-induced back-side doping. A guard-ring structure was introduced into the In anode electrode to realize an electron-collecting-type detector with a low leakage current, although pixelation on the In anode side was difficult. In the In/CdTe/Au p-n gamma-ray detector, rectification behavior was clearly observed, and the leakage current of the central electrode was 13 nA at a reverse voltage of 500 V. The energy spectra of Am-241 and Co-57 radioisotopes were collected at room temperature and showed energy resolutions (full width at half maximum) of 2.9 and 3.6 keV for gamma rays of 59.5 and 122 keV, respectively.