Dual Electrical Behavior of Multivalent Metal Cation-Based Oxide and Its Application to Thin-Film Transistors with High Mobility and Excellent Photobias Stability

Abstract

The effect of multivalent metal cations, including vanadium(V) and tin (Sn), on the electrical properties of vanadium-doped zinc tin oxide (VZTO) was investigated in the context of the fabrication of thin-film transistors (TFTs) using a single VZTO film and VZTO/ZTO bilayer as channel layers. The single VZTO TFT did not show any response to the gate voltage (insulator-like behavior). On the other hand, the VZTO/ZTO bilayer TFT exhibited a typical TFT transfer characteristic (semiconducting behavior). X-ray photoelectron spectroscopy revealed that, in contrast to what is commonly true in many oxides, oxygen vacancies (V(O)) in VZTO did not provide a dominant contribution to the total carrier concentration, because the V(O) peak area in the single VZTO film was 5.4% and reduced to 4.5% in VZTO/ZTO bilayer. Instead, Sn 3d5/2 and V 2p3/2 spectra suggest that the significant reduction in Sn and V ions is strongly related to the insulator-like behavior of the VZTO film. In negative-bias illumination tests and illumination tests with various photon energies, the VZTO/ZTO bilayer TFT had much better stability than the ZTO TFT. This result is attributed to the reduction of donor-like states ([Formula: see text]O) that can be positively ionized by blue and green illumination.

High-Performance Amorphous Zinc–Tin–Oxide Thin-Film Transistors With Low Tin Concentration

“…As shown in Fig. 2 stoichiometric oxidized bonds, oxygen vacancies (V o ) and chemisorbed oxygen, respectively [16], [22], [23]. Fig.…”

All‐Solution‐Processed Metal Oxide/Chalcogenide Hybrid Full‐Color Phototransistors with Multistacked Functional Layers and Composition‐Gradient Heterointerface

“…Thus, V o ‐suppressed Sn‐eqi a‐ZTO, which contains profuse Sn elements with high oxide binding energy (ZnO: 159 kJ mol −1 and SnO: 528 kJ mol −1 ), exhibits restrictive spectral/insensitive visible‐light response. In contrast, as shown in Figure d, CdS semiconductor with green‐light‐level direct optical bandgap (λ CdS, bandgap = 540 nm) contributes to a valuable photoresponse, owing to high‐efficiency exciton (electron–hole pair) generation via direct band‐to‐band visible‐light absorption under monochromic green/blue irradiation (λ Blue‐light = 450 and λ Green‐light = 550 nm) over the optical bandgap of CdS semiconductor [except red light (λ Red‐light ≈ 650 nm)].…”

Low voltage-driven oxide phototransistors with fast recovery, high signal-to-noise ratio, and high responsivity fabricated via a simple defect-generating process

“…When 400 nm monochromatic light with a power density of 0.1 mW cm −2 was illuminated on the devices for 3 min, the on-currents of both TFTs increased and the transfer curves shifted to the negative direction. This can be attributed to the photo-induced detrapped/ejected electrons from the interface as well as the photo-excited electrons from deep subgap states such as neutral oxygen vacancies (V O )3132, and/or band tail states32. More specifically, the V th for the low defect photo-TFT shifted by −1.2 V while the Δ V th for the high defect TFT was −5.5 V and unlike the low defect photo-TFT, the off-current increased by about 2 orders of magnitude.…”