Evidence of Improved Thermal Stability via Nanoscale Contact Engineering in IGZO Source-Gated Thin-Film Transistors

Despite rapidly expanding interest in thin-film source-gated transistors (SGTs), the high-temperature dependence of drain current (TDDC) in devices comprising Schottky source barriers is delaying wide adoption. To reduce this effect, alternative source designs have been theorized. Specifically, introducing additional nanoscale layers at the source contact should facilitate the tunneling of charge carriers at the Fermi energy level with negligible TDDC. Here, we fabricate amorphous In2Ga2ZnO7 tunnel-contact SGTs (TC-SGTs) with three times lower TDDC than polysilicon transistors with Schottky contacts. Numerical simulations help elucidate the control mech-anisms. We show that the potential profile across the semiconductor in the bulk of the source-gate overlap region determines injection current, and the introduction of a thin interfacial layer at the contact reduces the role of the contact metal work function (WF) in current control and associated temperature effects. This device architecture adds improved thermal stability to the long list of SGT benefits, including low voltage saturation, power-efficient operation, high intrinsic gain, device-to-device uniformity, and robustness to mechanical and electrical stress.

Automated summary

Despite the high-temperature dependence of drain current (TDDC) in devices with Schottky source barriers, alternative source designs, such as introducing additional nanoscale layers, have been theorized to reduce this effect. In this study, amorphous In2Ga2ZnO7 tunnel-contact SGTs (TC-SGTs) with lower TDDC were fabricated. Numerical simulations helped clarify the control mechanisms.