Frequency dependent electrical transport in bismuth-modified amorphous germanium sulfide semiconductors

摘要: Abstract AC conductivity of Bi-modified amorphous germanium sulfide semiconductors Ge20S80−xBix from 100 Hz to 10 kHz and in the temperature range 180–445 K is reported. The ac proportional ωs. In Ge20S80 composition, value σac(ω) depends linearly on frequency nearly independent temperature. samples containing Bi, increases with Bi content, especially at high low frequencies. dependence S all compositions examined interpreted by a correlated barrier hopping model (CBH). Analysis results reveals that electronic conduction unmodified (x = 0, 4) takes place via bipolaron hopping. Addition higher concentrations induces new types defects which take part single polaron process. Following Phillip's constraint theory cluster model, modified glass has microclusters Bi2S3 tetradymite structure, embedded matrix GeS2 (S)n. These may have n-type situated excess S− atoms surface; these defect be taking