As-doped p-type ZnO films by sputtering and thermal diffusion process

Abstract

As-doped p-type ZnO films were grown on GaAs by sputtering and thermal diffusion process. Hall effect measurements showed that the as-grown films were of n-type conductivity and they were converted to p-type behavior after thermal annealing. Moreover, the hole concentration of As-doped p-type ZnO was very impressible to the oxygen ambient applied during the annealing process. In addition, the bonding state of As in the films was investigated by x-ray photoelectron spectroscopy. This study not only demonstrated an effective method for reliable and reproducible p-type ZnO fabrication but also helped to understand the doping mechanism of As-doped ZnO.

Fabrication of As-doped p-type ZnO thin films using As2O3 as doping source material by E-beam evaporation

“…A broad peak corresponding to 42.2-42.7 eV was observed in the as-grown film. The peak appeared at this binding energy region may be attributed to amorphous elemental As [12]. XPS spectra of As 3d core level at 45.6 eV was detected for the annealed films.…”

An alternative approach to investigate the origin of p-type conductivity in arsenic doped ZnO

“…Arsenic is more volatile than gallium and thus it starts to diffuse at a lower annealing temperature. This method was successfully used by Cheng et al [13] and Wang et al [15] to achieve p-type conductivity in ZnO with a hole concentration of around 10 20 cm À3 . From the literature, it is observed that such a large carrier concentration was not achieved by any other means.…”

“…Arsenic can also be doped into ZnO, by using GaAs as the substrate as well as the source of arsenic. Directional thermal treatment of the samples (ZnO/GaAs) facilitates diffusion of arsenic from GaAs substrate into ZnO films [13,15]. Arsenic is more volatile than gallium and thus it starts to diffuse at a lower annealing temperature.…”

“…In addition to metal organic chemical vapor deposition (MOCVD) [8e12] and atomic layer deposition [13], several other techniques, such as ion implantation [14], radio frequency magnetron sputtering [15,16], pulsed laser deposition [17], etc. have been used successfully to obtain arsenic doped p-type ZnO.…”

Photoluminescence and diode characteristic of ZnO thin films/junctions fabricated by pulsed laser deposition (PLD) technique

“…In recent years, group V elements, such as N, P, As, and Sb were utilized as p-type dopants to form rather stable ptype ZnO films [1][2][3][4]. In particular, rapid thermal annealing and the post annealing converted semi-insulating ZnO:P films into stable and reproducible p-type ZnO:P ones [5,6].…”