Electrical properties of In-doped ZnO films grown by plasma-assisted molecular beam epitaxy on GaN(0001) template

Indium doped ZnO films have been successfully deposited on high resistivity GaN(0001) templates by plasma-assisted molecular beam epitaxy. N-type ZnO with carrier concentration of 4.35x10(20) cm(-3) and electron mobility of 5.7 cm/V-s, leading to resistivity of 2.6x10(-3) Omega-cm, are measured by Hall measurements. Under low indium doping flux, the carrier concentration increases accordingly with indium cell temperature until a max concentration is achieved as it might reach the In solubility. Further increase in doping flux leads to lower carrier concentration. X-ray diffraction spectra also show the degraded crystal quality as In doping concentration increases. Low temperature photoluminescence indicates that donor bound excitons dominate the emission while deep level emissions are not present in our In-doped ZnO films.