Density-Dependent Microstructures and Electromechanical Properties of Amorphous InGaZnO₄ Semiconductors: An Ab Initio Study

Abstract

Amorphous oxide semiconductors have been applied to thin-film electronics on the backplanes of organic light-emitting diode (OLED) displays. In mobile and high-refresh-rate display applications, demands have been increasing for both low power consumption and high operation speed of the electronics. Here, based on ab initio calculations, we suggest that density engineering of amorphous InGaZnO 4 semiconductors can improve electrical properties. The density of an amorphous material is typically variable over a wide range through process control as well as device design and mechanical operation. It is shown here that increasing the density (up to 6.4 g/cm 3 ) of amorphous InGaZnO 4 semiconductors with respect to the conventional density (5.8 g/cm 3 ) widens the electronic energy gap by +3.8% and reduces the effective mass of electrons by −4.3%, simultaneously. In a wide range of 3.6−7.8 g/cm 3 , the electrical properties are found to vary nonmonotonically, of which the physical mechanisms combined with the microstructures are investigated in depth. Density optimization can ultimately lead to both a reduction of off-state current and an enhancement of electron mobility in amorphous InGaZnO 4 -based thin-film transistors.

The Mechanism of the Photostability Enhancement of Thin-Film Transistors Based on Solution-Processed Oxide Semiconductors Doped with Tetravalent Lanthanides

“…As a result, the Ln 4+ can more easily absorb light than V O . The results reveal that the improvement of the NBIS stability of the Pr/Tb:In 2 O 3 TFTs is attributed to the absorption of the illuminated light by the Ln4f n -O2p 6 to Ln4f n+1 -O2p5 CT transition and downconversion of the light to nonradiative transition with a relatively short relaxation time compared to V O ionization. Minasian et al reported that the partially occupied 4f states are lower in energy than the unoccupied 5d states and provide band gaps of 2.3 and 1.7 eV for PrO 2 and TbO 2 , respectively[39].…”

“…Oxide semiconductors, such as InGaZnO 4 (IGZO) [ 1 , 2 , 3 , 4 , 5 ], have drawn considerable attention for the advantages of relatively high mobility, large-area processability, good uniformity, high transparency to visible light, etc. [ 6 ] In particular, the extremely low off current ( I off ) makes it attractive in energy-saving devices that require long stand-by time [ 7 ].…”

Applications of amorphous inorganics as novel functional materials

“…187 On the contrary, amorphous metallic oxide-based materials have caused a semiconductor-revolution since 2000 owing to their superior charge transport properties, also known as carrier mobility with a range of μ ∼ 1–100 cm 2 V −1 s −1 . 188 Compared with crystalline counterparts, amorphous metallic oxides demonstrate higher electron mobilities, which is elucidated by the electronic structure depicted. The ionic nature of oxides plays a significant role in this regard.…”