Control of the threshold voltage of polyvinylpyrrolidone-coated SnO2 nanowire transistor using xenon flash light irradiation

Abstract

It is necessary to maintain the threshold voltage (Vth) of all transistors constituting a logic circuit within a certain range during the fabrication of a logic circuit using n-type metal oxide nanowire transistors (NWTs). Herein, xenon flash light irradiation was used to control the number of oxygen vacancies in a polyvinylpyrrolidone-coated SnO2 nanowire, a semiconductor channel. Additionally, a method for maintaining the positively shifted non-ideal Vth of SnO2 NWT within the positive Vth range close to zero, by shifting it in the negative direction, was investigated. After the xenon flash light irradiation (100–500 V, 5 ms), a decrease in the oxygen content of the SnO2 nanowire was observed using energy-dispersive x-ray spectroscopy and an increase in the peak at ∼600 nm corresponding to the oxygen vacancies was noted in the photoluminescence measurements. The main advantage of using xenon flash light irradiation was that the negative shift of Vth could be controlled within the range of −0.25 V to −3.4 V without any change in other representative transistor characteristics such as subthreshold slope, on-current, on–off current ratio, and field effect mobility of the SnO2 NWT. In addition, by applying the self-assembled monolayers of (1H,1H,2H,2H-heptadecafluorodec-1-yl)phosphonic acid on the SnO2 nanowire surface to serve as a passivation layer, the negatively shifted Vth of the SnO2 NWT induced by the Xe flash light irradiation could be stably maintained without being affected by environmental oxygen and moisture.