Jiang Y C, Gao J
Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
Sci Rep. 2014 Oct 23;4:6738. doi: 10.1038/srep06738.
Traditionally, strain effect was mainly considered in the materials with periodic lattice structure, and was thought to be very weak in amorphous semiconductors. Here, we investigate the effects of strain in films of cobalt-doped amorphous carbon (Co-C) grown on 0.7PbMg(1/3)Nb(2/3)O3-0.3PbTiO3 (PMN-PT) substrates. The electric transport properties of the Co-C films were effectively modulated by the piezoelectric substrates. Moreover, we observed, for the first time, strain-induced photoconductivity in such an amorphous semiconductor. Without strain, no photoconductivity was observed. When subjected to strain, the Co-C films exhibited significant photoconductivity under illumination by a 532-nm monochromatic light. A strain-modified photoconductivity theory was developed to elucidate the possible mechanism of this remarkable phenomenon. The good agreement between the theoretical and experimental results indicates that strain-induced photoconductivity may derive from modulation of the band structure via the strain effect.
传统上，应变效应主要在具有周期性晶格结构的材料中被考虑，并且被认为在非晶半导体中非常微弱。在此，我们研究了生长在0.7PbMg(1/3)Nb(2/3)O3 - 0.3PbTiO3（PMN - PT）衬底上的钴掺杂非晶碳（Co - C）薄膜中的应变效应。钴掺杂非晶碳薄膜的电输运特性被压电衬底有效地调制。此外，我们首次在这种非晶半导体中观察到应变诱导的光电导性。在没有应变的情况下，未观察到光电导性。当受到应变时，钴掺杂非晶碳薄膜在532纳米单色光照射下表现出显著的光电导性。我们发展了一种应变修正的光电导理论来阐明这一显著现象的可能机制。理论和实验结果之间的良好一致性表明，应变诱导的光电导性可能源于通过应变效应对价带结构的调制。
