Permanent optical doping of amorphous metal oxide semiconductors by deep ultraviolet irradiation at room temperature

We report an investigation of two photon ultraviolet (UV) irradiation induced permanent n-type doping of amorphous InGaZnO (a-IGZO) at room temperature. The photoinduced excess electrons were donated to change the Fermi-level to a conduction band edge under the UV irradiation, owing to the hole scavenging process at the oxide interface. The use of optically n-doped a-IGZO channel increased the carrier density to similar to 10(18) cm(-3) from the background level of 10(16) cm(-3), as well as the comprehensive enhancement upon UV irradiation of a-IGZO thin film transistor parameters, such as an on-off current ratio at similar to 10(8) and field-effect mobility at 22.7 cm(2)/V s. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3429586]