Stretched-exponential photoionization of the metastable defects in gallium doped Cd 0.99 Mn 0.01 Te : Statistical origins of the short-time power-law in response data

• Published in: Journal of applied physics 2008-06, Vol.103 (11), p.114902-114902-7
• Main Authors: Trzmiel, J., Weron, K., Placzek-Popko, E.
• Format: Article
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.2936984

The subject of the present study is the low temperature nonexponential transients of photoconductivity build-up in gallium doped Cd 0.99 Mn 0.01 Te semiconducting mixed crystals possessing metastable defects, so called DX centers. The phototransients were analyzed in terms of two approaches. The first one was the two-exponential fitting that is usually applied to explain the persistent photoeffect build-up in materials with DX centers. The second, implemented in the above-mentioned semiconductors, was the stochastic model of relaxation leading to the stretched-exponential result. The latter fitting was found to be more appropriate for it justifies the short-time power-law exhibited by the phototransient response. According to the stochastic approach this behavior results from a heavy-tailed distribution of photoionized DX centers. The distribution can have its origin in different local arrangements.