Luminescence properties of semi-insulating nominally-undoped CdTe crystals

CdTe crystals were grown by the vapour phase and by Bridgman method by using hihg purity and stoichiomety controlled source material. Nominally undoped high resistivity crystals were reproducibly obtained. A detailed photoluminescence (PL) analysis was carried out in order to investigate the compensation mechanism of the crystals. PL spectra are dominated by the bound acceptor exciton line at 1.588 eV, showing a "p" type character. A line at 1.583 eV is also present possibly due to III group impurities. A week 1.4 eV band was also revealed.