Ti-Doped Indium Tin Oxide Thin Films for Transparent Field-Effect Transistors: Control of Charge-Carrier Density and Crystalline Structure

Abstract

Indium tin oxide (ITO) films are representative transparent conducting oxide media for organic light-emitting diodes, liquid crystal displays, and solar cell applications. Extending the utility of ITO films from passive electrodes to active channel layers in transparent field-effect transistors (FETs), however, has been largely limited because of the materials' high carrier density (>1 × 10(20) cm(-3)), wide band gap, and polycrystalline structure. Here, we demonstrate that control over the cation composition in ITO-based oxide films via solid doping of titanium (Ti) can optimize the carrier concentration and suppress film crystallization. On 120 nm thick SiO(2)/Mo (200 nm)/glass substrates, transparent n-type FETs prepared with 4 at % Ti-doped ITO films and fabricated via the cosputtering of ITO and TiO(2) exhibited high electron mobilities of 13.4 cm(2) V(-1) s(-1), a low subthreshold gate swing of 0.25 V decade(-1), and a high I(on/)I(off) ratio of >1 × 10(8).

Eco-friendly water-induced aluminum oxide dielectrics and their application in a hybrid metal oxide/polymer TFT

“…Generally, strong oxygen-binding cations, e.g., X ¼ Y, 18 Ga, 11,19 Ti, 20 and Al, 21 are introduced into In 2 O 3 host as matrix dopants to adjust the carrier concentration. Generally, strong oxygen-binding cations, e.g., X ¼ Y, 18 Ga, 11,19 Ti, 20 and Al, 21 are introduced into In 2 O 3 host as matrix dopants to adjust the carrier concentration.…”

Electrical, Structural, Optical, and Adhesive Characteristics of Aluminum-Doped Tin Oxide Thin Films for Transparent Flexible Thin-Film Transistor Applications

“…Chu et al reported that reduced carrier concentration in the n-type channel material induces higher V th and lower I off , because the channel with lower carrier concentration is more easily depleted [18]. Therefore, these positive shifts of V th and decreased I off are attributable to reductions in electron density in the TFT channels as Al levels increase [2,6,18,19]. In general, oxygen vacancies in SnO x -based materials generate free electrons, which is accompanied by n-type semiconduction [20,21].…”

“…In recent years, intensive research efforts have focused on metal oxide semiconductors, such as ZnO, SnO 2 , In 2 O 5 , and InGaZnO 5 , which have many applications in electronics, sensors, and active matrix displays. Because of their high electron mobility and good transparency, metal oxide semiconductors are especially ideal candidates for the active layers of thin-film transistors (TFTs) [1,2,3,4,5,6,7]. Most metal oxide semiconductors are fabricated via sputtering; their properties are determined by reactions between the injected gases (Ar and O 2 ) and the metals (e.g., In, Sn, Zn, and Ga), typically yielding amorphous, conductive, and transparent materials.…”

Titanium doped Zinc-oxide based Thin Film Transistors: Optimization of the source/drain materials

“…However, both Indium element and Gallium element are toxicant and rare element in the earth, which is not only very expensive but also harmful to our body. In this experiment, we choose Titanium-doped Zinc Oxide as the active layer, as Titanium dopants in Zinc-Oxide are able to suppress the generation of free carriers and obtain an optimal carrier concentration, thus optimizing the electrical performances of the TFTs [7][8][9]. Besides, both Titanium element and Zinc element are non-toxic, cheap and abundant in the earth.…”