Evidence of p-doping in ZnO films deposited on GaAs

Abstract

Successful p-type ZnO thin films have been reported by depositing it on semi insulating GaAs substrates by Pulsed Laser Deposition (PLD) technique. The PLD samples were subsequently subjected to Rapid Thermal Annealing to achieve the required doped ZnO. X-ray Diffraction, Atomic Force Microscopy and Van der Pauw Hall measurements were performed on the annealed samples and compared with as-deposited ones. The XRD results confirm growth of <002> ZnO along with better crystallinity for the annealed sample. The AFM results reveal that the thin films deposited were highly uniform having very low roughness values. Van der Pauw Hall measurements show a transition from n-type conductivity for as-deposited sample to p-type for annealed samples. The hole concentration and Hall mobility measured were reported to be as high as 4.475 × 10 20 cm − 3 and 39.73 cm 2/V-sec respectively. These are probably the highest reported values to date and are encouraging from the point of successful fabrication of efficient ZnO-based optoelectronics devices like LED, laser, photodiodes, etc. in the near future.