Prof. Yi Gu
Department of Physics and Astronomy, Washington State University, Pullman, WA
Charge carrier transport plays a central role in semiconductor-based device operations. The minority carrier transport is particularly important, as it controls the majority carrier transport and thus the current characteristics in p-n junctions, a fundamental element in many semiconductor devices including solar cells, photodetectors, light emitting diodes, and lasers. As the device dimension continues to decrease in the nanometer regime, surface effects become a significant factor in limiting carrier transport.
Here we present our recent efforts in using various scanning probe-based techniques and finite-element simulations to delineate the relative significance of surface and bulk effects in carrier transport in ZnO nanowires. Our findings suggest that this relative significance depends strongly on the nanowire diameter. This strong diameter dependence cannot be accounted for by the surface-to-volume ratio alone, and the diameter dependence of the surface state density plays a critical role. These results enable important insight into the underlying mechanisms of surface effects and provide a basis for advancing nanowire-based device technologies.