Majority‐carrier mobilities in undoped and n ‐type doped ZnO epitaxial layers

Abstract

Transparent and conductive ZnO:Ga thin films are prepared by laser molecular-beam epitaxy. Their electron properties were investigated by the temperature-dependent Hall-effect technique. The 300-K carrier concentration and mobility were about ns ∼ 10 16 cm −3 and 440 cm 2 /Vs, respectively. In the experimental 'mobility vs concentration' curve, unusual phenomenon was observed, i.e., mobilities at n s ∼ 5× 10 18 cm −3 are significantly smaller than those at higher densities above ∼ 10 20 cm −3 . Several types of scattering centers including ionized donors and oxygen traps are considered to account for the observed dependence of the Hall mobility on carrier concentration. The scattering mechanism is explained in terms of inter-grain potential barriers and charged impurities. A comparison between theoretical results and experimental data is made.

Effects of growth temperature and oxygen pressure on the properties of heteroepitaxial ZnO thin films on sapphire (0001) substrates by pulsed laser deposition

“…In addition, we expect that due to the small thickness of the films, grain boundaries and defects near the interface region may prominently influence the electrical property. The grain boundaries might contain fairly high density of interface states which trap free carriers from the bulk of the grains, resulting in a reduction in Hall mobility [11].…”

Hole Transport in p-Type ZnO

“…A dislocation scattering and the space-charge effect probably also contribute as a scattering mechanism of holes to the mobility determination. Actually, it is known that the former mechanism have an influence on relatively-poor-quality n-type ZnO epitaxial layers 21 . We would like to propose more experiments using further optimized samples be done in future.…”

“…type ZnO epitaxial layers. 21) We propose that more experiments using further-optimized samples be performed in the future.…”

Electron transport and low-temperature electrical and galvanomagnetic properties of zinc oxide and indium oxide films

“…5,6 The effect of structural perfection on the properties of zinc and indium oxide films is still a topic of research, both because of the difficulty of reproducing experimental data and because of the complexity of interpreting these data in terms of existing models for electron transport in wide-bandgap semiconductors. For this reason, studies of the conducting properties of zinc and indium oxide films are of fundamental interest.…”