The electrical, optical, and structural properties of amorphous indium gallium zinc oxide films and channel thin-film transistors

Abstract

The electrical, optical, and structural properties of amorphous indium gallium zinc oxide (a-IGZO) films deposited at room temperature (RT) examined before and after annealing using a radio frequency (RF) magnetron sputtering system with different hydrogen and oxygen gas flow ratios. The carrier concentration and resistivity of the a-IGZO films fabricated under O2/Ar+O2 and O2/Ar–4%H2+O2 atmospheres were greatly dependent on the addition of hydrogen and heat treatment. Thin-film transistors (TFTs) with an a-IGZO channel layer deposited under O2/Ar–4%H2+O2=1.6% exhibited good subthreshold gate voltage swing (S), on/off ratio, threshold voltage and μFE of 0.4Vdecade−1, 108, 0.3V and 4.8cm2V−1s−1, respectively. From analysis of the interfacial structure in TFTs before and after annealing, the electrical conductivity of the a-IGZO channel layer was greatly affected in regard to TFT performance due to the amorphous a-IGZO channel layer and SiO2 gate insulator.