[1] St Petersburg Electrotech Univ LETI, Dept Micro & Nanoelect, St Petersburg 197376, Russia
[2] St Petersburg Acad Univ, Renewable Energy Lab, St Petersburg 194021, Russia
[3] Russian Acad Sci, Ioffe Phys Tech Inst, Lab Physicochem Properties Semicond, St Petersburg 194021, Russia
[4] CJSC Svetlana Rost, St Petersburg 194156, Russia