Grain-boundary-controlled transport in GaN layers

Abstract

An exponential dependence of the photoconductivity on the surface photovoltage at GaN layers is predicted theoretically and confirmed experimentally. The prediction is based on the assumption that the material is mainly an ordered polycrystal, consisting of columnar grains. Accordingly, transport is expected to be limited by potential barriers at the grain boundaries, arising from the charge trapped at grain-boundary defects. The observed exponential dependence provides evidence that strongly supports the model by establishing a direct link between the bulk conductivity and the surface potential barrier. The same model is shown to successfully explain several other defect-related findings as well.

The Effect of Grain Boundaries on Electrical Conductivity in Thin GaN Layers

“…The experimental details as well as a derived relation between the height of the grain boundary barriers and the surface potential barrier will be reported elsewhere [13].…”

Electrical and optical properties of ZnO films grown by molecular beam epitaxy

“…It is accepted that dangling bonds, surface defects or some impurities will concentrate at the grain boundaries [10]. However, how the grain boundaries will affect the optical and electrical properties of the ZnO films has not been demonstrated clearly yet, although it is of vital significance and importance in obtaining high structural and optical quality ZnO [11][12][13].…”

Photoinduced Kondo effect inCeZn3P3

“…If ρ photo (T) due to the photoinduced lowering of a grain-boundary potential-barrier shows an upturn below a certain temperature, it was hence found to approximately follow a thermal activation-type trend 39 . Therefore, ρ photo produced by only grain boundary effects cannot explain ρ photo (T) of CeZn 3 P 3 showing an -lnT behavior.…”

“…Additional influential candidates within the realm of carrier trapping, however, were acknowledged during the assessment process. One associated candidate was the grain boundary 39 , while the other candidate was the energy-band grouping far above the lowest conduction band level. The density of states for the latter is resultantly sufficient to sustain a carrier concentration of 10 21 cm −3 (see also Fig.…”