Toshio Kamiya

The present status and recent research results on amorphous oxide semiconductors (AOSs) and their thin-film transistors (TFTs) are reviewed. AOSs represented by amorphous In-Ga-Zn-O (a-IGZO) are expected to be the channel material of TFTs in next-generation flat-panel displays because a-IGZO TFTs satisfy almost all the requirements for organic light-emitting-diode displays, large and fast liquid crystal and three-dimensional (3D) displays, which cannot be satisfied using conventional silicon and

Amorphous oxide semiconductors (AOSs) are expected as new channel materials in thin-film transistors (TFTs) for large-area and/or flexible flat-panel displays and other giant-microelectronics devices. So far, many prototype displays have been demonstrated in these four years since the first report of AOS TFT. The most prominent feature of AOS TFTs is that they operate with good performances even if they are fabricated at low temperatures without a defect passivation treatment. The TFT mobilities

Amorphous oxide semiconductors (AOSs) are expected as new channel materials in thin-film transistors (TFTs) for large-area and/or flexible flat-panel displays and other giant-microelectronics devices. So far, many prototype displays have been demonstrated in these four years since the first report of AOS TFT. The most prominent feature of AOS TFTs is that they operate with good performances even if they are fabricated at low temperatures without a defect passivation treatment. The TFT mobilities

Electronic structures and carrier transport mechanisms in disordered oxide semiconductors, crystalline InGaO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (ZnO) <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</i> ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">m</i> = 1, 5) (c-IGZO) and amorphous InGaZnO <sub xmlns:mml="http://www.w3.org/1998/Math

Abstract This paper discusses an optical model and subgap electronic states for a representative amorphous oxide semiconductor, InGaZnO 4 (a‐IGZO). Parameterized optical models were developed based on the Tauc–Lorentz model combined with a Lorentz‐type oscillator. The measured optical absorption spectra exhibit nearly linear dependences on photon energy ( E ) between 3 eV &lt; E &lt; 5 eV, which requires the transition energies in the Tauc–Lorentz model ( E 0,TL ) being around 4 eV. The optimize

Abstract Defect states in a representative amorphous oxide semiconductor, a‐InGaZnO 4 , were studied by optical analyses and first‐principle calculations. The optical analyses suggested that the as‐deposited a‐IGZO film have weak subgap absorptions around 0.6 and 2 eV. Local density approximation calculations showed that an oxygen defect works as an electron trap as well as a shallow donor depending on its local structure. It suggests that a large vacancy space remained in an oxygen deficient st

Cs2SnI6, a rarely studied perovskite variant material, is recently gaining a lot of interest in the field of photovoltaics owing to its nontoxicity, air-stability and promising photovoltaic properties. In this work, we report intrinsic defects in Cs2SnI6 using first-principles density functional theory calculations. It is revealed that iodine vacancy and tin interstitial are the dominant defects that are responsible for the intrinsic n-type conduction in Cs2SnI6. Tin vacancy has a very high form

Abstract Amorphous In‐Ga‐Zn‐O (a‐IGZO) is expected for channel layers in thin‐film transistors (TFTs). It is known that a‐IGZO is sensitive to an O/H‐containing atmosphere; therefore, it is important to clarify the roles of oxygen and hydrogen in a‐IGZO. This paper provides atomic and electronic structures, formation energies of defects and bond energies in a‐IGZO calculated by first‐principles density functional theory (DFT). It was confirmed that oxygen deficiencies having small formation ener