Reversible UV induced metal–semiconductor transition in In₂O₃thin films prepared by autowave oxidation

Abstract

We have prepared thin indium oxide films by the autowave oxidation reaction. Measurements of temperature dependence of resistivity, Hall carrier concentration and Hall mobility have been conducted in the temperature range 5-272 K. Before ultraviolet (UV) irradiation, the indium oxide film had a semiconductor-like temperature dependence of resistivity ρ and the ratio of ρ (5 K)/ρ(272 K) was very limited (∼1.2). It was found that after UV irradiation of the In 2 O 3 film, the metal-semiconductor transition (MST) was observed at ∼100 K. To show that this MST is reversible and repeatable, two full cycles of 'absence of MST-presence of MST' have been done using UV irradiation (photoreduction) as the induced mechanism and exposure to an oxygen environment as the reversible mechanism, respectively. MST in transparent conducting oxide (TCO) is possibly associated with the undoped structure of metal oxide, which has some disorder of oxygen vacancies. It was suggested that reversible UV induced metal-semiconductor transition would occur in other TCOs.

Temperature-dependent Photoconductance and Optical Properties of In2O3 Thin Films Prepared by Autowave Oxidation

“…The band gap of the indium oxide films, depending on the method of preparation, can vary from 3.5 eV (355 nm) to 4 eV (310 nm) [5], which is consistent with our measurements [45].…”

Weak localization and size effects in thin In 2 O 3 films prepared by autowave oxidation

“…In addition, the indium oxide film had a limited ratio of resistances measured at 5 K and 272 K (~1.2). Furthermore, it has been shown that ultraviolet irradiation can induce MST in the indium oxide film [36]. Thus, we expect that the weak localization effect and the related negative magnetoresistance can be observed in thin In 2 O 3 films prepared by autowave oxidation.…”

Photovoltaic Conversion Enhancement of a Carbon Quantum Dots/p-Type CuAlO2/n-Type ZnO Photoelectric Device

“…As known, the foundation of this type of device is TCO (Transparent Conducting Oxide). Up to now, lots of n-type TCO have been reported 6,7 , Such as ZnO, In 2 O 3 , but the lack of p-type TCO restricted the development of the transparent photoelectric device. Although GaN etc.…”