Microscopic Understanding of the Carrier Transport Process in Ge Nanocrystals Films

Abstract EN

Hydrogenated amorphous germanium ( a -Ge:H) films were prepared by a plasma enhanced chemical vapor deposition (PECVD) technique.

Ge nanocrystals (Ge NCs) films were obtained by thermal annealing of the as-deposited samples at various temperatures.

P-type behavior in Ge NCs films without any external doping was attributed to the holes accumulation caused by acceptor-like surface states.

It can be found that the dark conductivity and Hall mobility reached as high as 25.6 S/cm and 182 cm2/V·s in the Ge NCs film annealed at 500°C, which were increased by over four and three orders of magnitude higher than that of the as-deposited film (1.3 × 10-3 S/cm and 0.14 cm2/V·s, resp.).

Carrier transport mechanisms of Ge NCs films association with the microstructural characteristics were investigated.

Three kinds of temperature-dependent conductivity behaviors, which exhibit the linear relationships of ln σ versus T - 1 / 4 , T - 1 / 2 , and T - 1 , respectively, were observed in the temperature regions from 10 K to 500 K, showing different microscopic mechanisms governing carrier transport in Ge NCs film.