High resistivity In-doped ZnTe: electrical and optical properties |
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Authors: | D N Bose S Bhunia |
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Affiliation: | (1) University Science Instrumentation Centre, Calcutta University, 700 009 Kolkata, India;(2) Department of Physics, Indian Institute of Technology, 400 076 Mumbai, India |
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Abstract: | Semi-insulating <111> ZnTe prepared by In doping during Bridgman growth was found to have a resistivity of 5.74 × 107 ohm-cm, the highest reported so far in ZnTe, with hole concentration of 2.4 × 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 202–222 meV and 412–419 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 p-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. |
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Keywords: | II– VI compound ZnTe |
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