Activation of phosphorous doping in high quality ZnO thin film grown on Yttria-stabilized zirconia (1 1 1) by thermal treatment

Abstract

Phosphorous doped (P-doped) ZnO thin films are grown on c-sapphire and Yttria-stabilized zirconia (YSZ) (111) substrates by pulsed laser deposition. Post growth annealing is carried out to activate phosphorous to act as acceptor. The rocking curve of annealed P-doped ZnO films grown on YSZ (111) has full width at half maximum of 0.08°, more than two times narrower than that of the as-grown one. Neutral acceptor bound exciton (A 0X) is observed from low temperature photoluminescence with estimated activation energy of 11.3 meV. Low carrier concentration of as-grown P-doped ZnO films indicated phosphorous doping creates acceptor states and/or reduced the oxygen vacancies. The carrier concentration of annealed samples is reduced by five order magnitudes from 3.21 × 10 18 cm − 3 to 1.21–8.19 × 10 13 cm − 3 . At annealing temperature of 850 °C, the sample has the lowest carrier concentration and highest resistivity. This is an indication that the phosphorous in P-doped ZnO has been activated.