Tokyo Institute of Technology · Materials Science
Professor Toshio Kamiya's research lab specializes in the development and fundamental understanding of amorphous oxide semiconductors (AOS), with a primary focus on their electronic structures, carrier transport mechanisms, and defect physics. The lab investigates materials such as amorphous In-Ga-Zn-O (a-IGZO) for next-generation thin-film transistors (TFTs) used in large-area, flexible, and high-performance flat-panel displays and giant-microelectronics. Key research directions include optical characterization, subgap electronic states, defect engineering, and the optimization of low-temperature fabrication processes without defect passivation. The lab combines experimental techniques with first-principles calculations to advance the performance and stability of oxide semiconductor devices.
Figures are computed from collected data and may differ slightly.
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 < E < 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
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