Performance Enhancement of IGZO Thin-Film Transistors by Ultrathin Te Back-Channel Heterojunction Capping

UUltrathin p-type capping layers were introduced to modulate the back-channel surface of IGZO thin-film transistors (TFTs). Among Te, NiOx, and SnOx capping layers, the Te-capped IGZO TFT exhibits the best balanced performance, with a subthreshold swing (SS) of 67.1 mV/dec, a field-effect mobility (μFE) of 25.6 cm2/V·s, an on/off current (Ion/Ioff) ratio of 1.06×109, and a threshold voltage (VTH) of −0.035 V. Compared with the control device, Te capping reduces SS by 63%, enhances μFE by 43%, and shifts VTH positively by 0.945 V. The Ion/Ioff ratio also increases by 49.3 times. The 2-nm Te layer therefore enables simultaneous improvement in switching steepness, carrier transport, and VTH control through back-channel modulation.