Unraveling the mechanism of ultraviolet-induced optical gating in Zn_1−xMg_xO nanocrystal solid solution field effect transistors

Abstract

We report ultraviolet (UV)-induced optical gating in a Zn1−xMgxO nanocrystal solid solution (NCSS) field effect transistor (FET) through a systematic study in which UV-induced charge transport properties are probed as a function of Mg composition. Change in the electrical properties of Zn1−xMgxO NCSS associated with electronic traps is investigated by field effect-modulated current–voltage characteristic curves in the dark and under illumination. Under UV illumination, significant threshold voltage shift to a more negative value in an n-channel Zn1−xMgxO NCSS FET is observed. Importantly, as the Mg composition increases, the effect of UV illumination on the threshold voltage shift is alleviated. We found that threshold voltage shift as a function of Mg composition in the dark and under illumination is due to difference in the deep trap density in the Zn1−xMgxO NCSS. This is supported by Mg composition dependent photoluminescence intensity in the visible range and reduced FET mobility with Mg addition. The presence of the deep traps and the corresponding trap energy levels in the Zn1−xMgxO NCSS are ensured by photoelectron spectroscopy in air.

Ambipolar Charge Carrier Transport Properties at the S-Benzyl-l-cysteine-Induced 2D/3D Halide Perovskite Interface

“…Saturation of the drain current at a high drain voltage results from the "pinch off" process. 24 Without SBLC, the magnitude of the drain current was not dependent on the gate voltage, as shown in Figure 3c. Linear and saturation transport regimes were not observed, confirming that the drain current is not tuned by the gate voltage.…”

“…The drain current linearly increased at a low drain voltage (linear transport regime) followed by current saturation at a high voltage (saturation transport regime). Saturation of the drain current at a high drain voltage results from the “pinch off” process . Without SBLC, the magnitude of the drain current was not dependent on the gate voltage, as shown in Figure c.…”