Preparation of amorphous Ga–Sn–Zn–O semiconductor thin films by RF-sputtering method

Ga–Sn–Zn–O (GTZO) thin films were deposited on glass substrates via the radio-frequency (RF) magnetron sputtering method at room temperature. The target for the GTZO film deposition was a single GaSnZnO pellet. Various oxygen gas content levels in the sputtering gas ambient (0, 3.8, 7.4, and 10.7%) were used in the deposition experiments. The resistivity of GTZO films decreased from 78 to 19.5 Ω cm when the oxygen content was decreased from 10.7 to 0%. The carrier concentration significantly decreased from 1.81 × 1017 cm−3 to 5.98 × 1015 cm−3 when the oxygen content was increased from 0 to 10.7%. Incorporating oxygen into GTZO films suppresses oxygen vacancy formation, resulting in a reduction of generated free carriers. The mobility increases rapidly with increasing oxygen pressure. The highest mobility of 13.3 cm2/V s was obtained at a carrier concentration of 5.98 × 1015 cm−3.