Article ID: 19134
As ionization potential (Ip) and electron affinity tunable amorphous oxide semiconductors, n-type amorphous Cd–In–Ga–O thin films are fabricated on SiO2 glass substrates by radio-frequency magnetron sputtering method. The Ip and electron affinity of the thin films are determined using ultraviolet photoelectron spectroscopy and ultraviolet–visible-near-infrared spectroscopy. The Ip is tuned from 6.5 to 7.1 eV by varying Ga concentration from ∼20 to ∼50%. In addition, the electron affinity shifts from 3.8 to 4.3 eV by varying Cd concentration. Carrier concentration and mobility strongly depend on Cd concentration for Cd concentrations greater than 50%. Carrier concentration (mobility) decreases (increases) with increasing Cd concentration. In contrast, the influence of Ga concentration seems to be greater for Cd concentrations less than 50%. Carrier concentration varies in the range of 1017 to 1020 cm−3. The maximum value of the mobility is 16 cm2 V−1 s−1.