Investigation of the electrical performance and carrier transport mechanism for heterostructured bilayer In2O3/InGaSnO thin-film transistors

Abstract

In this study, InGaSnO (IGTO)-based bilayer In2O3/IGTO and IGTO/In2O3 thin-film transistors (TFTs) were designed, and their carrier transport mechanisms and electrical performances were investigated. Herein, the ultrathin In2O3 layer provided a higher carrier concentration (Ne), thus accumulating free carriers and enhancing the carrier mobility. The thick amorphous IGTO layer controlled the device and carrier conductance, yielding a reasonable threshold voltage (Vth). Consequently, the optimized bilayer In2O3/IGTO TFTs exhibited high field-effect mobility (μFE) of 43.6 cm2 V−1s−1 and good control with Vth of 1.2 V compared to the single layer In2O3 and IGTO TFTs. Experimental analysis indicated a decrease in the oxygen vacancy (VO) formation energy owing to the interaction between interstitial Ini and Sn. Consequently, numerous unpaired electrons were generated from VO at the hetero-interfaces. In addition, an analysis of the energy band shift indicated that the heterojunction generated parasitic channels to control the Ne, and the In2O3/IGTO TFT exhibited a smaller Rc (0.34 KΩ μm), which enhanced the μFE of TFTs. Overall, the high-performance bilayer In2O3/IGTO TFTs fabricated herein have significant potential for applications in thin-film electronics.