Investigation on Physical Properties of IGZO Thin Films under the Conditions of Mixing Oxygen and Argon

Abstract

Amorphous indium gallium zinc oxide (IGZO) is the most suitable material choice for optoelectronic devices such as thin film transistor (TFT). However, usually, the physical properties of IGZO are of concern rather than the preparation process, which will complicate the control of the main properties of the material. To obtain a simple method of controlling IGZO properties, different proportions of mixed gases of oxygen and argon were added in the process of preparing thin films by pulsed laser deposition (PLD) for studying the fluence of atmosphere on the growth of IGZO. The structure and components of the film are characterized by X-ray diffraction (XRD), which confirmed the amorphous structure. A red-shift of the absorption peak in range of 450–850 nm was generated with the increase in argon concentration. Meanwhile, the transmission spectra showed that the transmittance of the material was lower than 80% in the range of 450–850 nm. Then, different target samples have a wide photoluminescence band at 200–800 nm. Oxygen vacancy defects were considered to be closely related to the photoluminescence behavior. The smallest surface roughness of the films prepared under 50% Ar and 50% O2 and the largest in 100% Ar are proved by atom force microstructure (AFM). Importantly, the greater difference in electrical properties reflects the sensitivity of different oxygen and argon concentrations to material effects. The carrier concentration can be adjusted from 1.08 × 1011 to 1.33 × 1016 by this method. Finally, the IGZO achieved in this work was used in a transistor, which reflected good diode characteristics.