The silicon/poly(3, 4-ethylenedioxythiophene) core/shell organic/inorganic nanowire array (SiNWs/PEDOT) hybrid heterojunction solar cells are successfully fabricated by silver-assisted chemical etching method and vapor phase polymerization processes. The SiNWs/PEDOT hybrid solar cell shows that the performance is improved greatly and an excellent power conversion efficiency of 3.23% is achieved, which is as seven times as large as that of the planar cell without the nanowire structure. In addition, the studies of the reflectance, the I-V curve and the external quantum efficiency show that the great enhancement of performance for the SiNWs/PEDOT cell is due to the fact that the Si/PEDOT core/shell nanowire structure is successfully fabricated by vapor phase polymerization method, resulting in a high light trapping effect, a large junction area and an enhancement of the carrier collection efficiency.

The magnetotransport measurement is performed on a GaN/AlxGa1-xN heterostructure sample in a low temperature range of 1.4-25 K and at magnetic fields ranging from 0 T up to 13 T. Magnetoresistance of a two-dimensional electron gas confined in the heterostructure is investigated. The negative magnetoresistivity in the whole magnetic field range originates from the electron-electron interactions (EEIs), while the positive magnetoresistivity in the high field range results from the parallel conductance. The EEI correction terms, as well as the concentration and mobility of the parallel channel are obtained by fitting the experimental data. Furthermore, another method of calculation is used to check their accuracy.