High Performance p-type SnO thin-film Transistor with SiOx Gate Insulator Deposited by Low-Temperature PECVD Method

We have investigated the gate insulator effects on the electrical performance of p-type tin monoxide (SnO) thin-film transistors (TFTs). Various SnO TFTs are fabricated with different gate insulators of a thermal SiO2, a plasma-enhanced chemical vapor deposition (PECVD) SiNx, a 150 degrees C-deposited PEVCD SiOx, and a 300 degrees C-deposited PECVD SiOx. Among the devices, the one with the 150 degrees C-deposited PEVCD SiOx exhibits the best electrical performance including a high field-effect mobility (=4.86 cm(2)/Vs), a small subthreshold swing (=0.7 V/decade), and a turn-on voltage around 0 (V). Based on the X-ray diffraction data and the localized-trap-states model, the reduced carrier concentration and the increased carrier mobility due to the small grain size of the SnO thin-film are considered as possible mechanisms, resulting in its high electrical performance.