Optical and Electrical Properties of the Different Magnetron Sputter Power 300℃ Deposited Ga_2O_3-ZnO Thin Films and Applications in p-i-n α-Si:H Thin-Film Solar Cells

摘要

A compound of ZnO with 3 wt% Ga_2O_3 (ZnO: Ga_2O_3 = 97:3 in wt%, GZO) was sintered at 1400℃ as a target. The GZO thin films were deposited on glass using a radio frequency magnetron sputtering system at 300℃ by changing the deposition power from 50 W to 150 W. The effects of deposition power on the crystallization size, lattice constant (c), resistivity, carrier concentration, carrier mobility, and optical transmission rate of the GZO thin films were studied. The blue shift in the transmission spectrum of the GZO thin films was found to change with the variations of the carrier concentration because of the Burstein-Moss shifting effect. The variations in the optical band gap (E_g) value of the GZO thin films were evaluated from the plots of (αhv) = c(hv - E_G)~(1/2), revealing that the measured E_g value decreased with increasing deposition power. As compared with the results deposited at room temperature by Gong et al., (2010) the 300℃ deposited GZO thin films had apparent blue shift in the transmission spectrum and larger E_g value. For the deposited GZO thin films, both the carrier concentration and mobility linearly decreased and the resistivity linearly increased with increasing deposition power. The prepared GZO thin films were also used as transparent electrodes to fabricate the amorphous silicon thin-film solar cells, and their properties were also measured.