High resistivity In-doped ZnTe: electrical and optical properties

[摘要] Semi-insulating < 111 > ZnTe prepared by In doping during Bridgman growth was found to have a resistivity of 5.74 Ã�? 10⁷ ohm-cm, the highest reported so far in ZnTe, with hole concentration of 2.4 Ã�? 10⁹/cm³ and hole mobility of 46 cm²/V.s at 300 K. The optical band gap was 2.06 eV at 293 K compared with 2.26 eV for undoped semiconducting ZnTe. Thermally stimulated current (TSC) studies revealed 2 trap levels at depths of 202â€�??222 meV and 412â€�??419 meV, respectively. Photoluminescence (PL) studies at 10 K showed strong peaks at 1.37 eV and 1.03 eV with a weak shoulder at 1.43 eV. Short anneal for 3 min at 250°C led to conversion to a ð‘�?-type material with resistivity, 14.5 ohm-cm, indicating metastable behaviour. Raman studies carried out on undoped and In-doped samples showed small but significant differences. Possible models for semi-insulating behaviour and meta-stability are proposed.

[学科分类] 材料工程

[关键词] IIâ€�?�VI compound;ZnTe.