Electrical Properties and Structure of p-Type Amorphous Oxide SemiconductorxZnO·Rh2O3

Abstract

p‐Type conduction in amorphous oxide was firstly found in zinc rhodium oxide (ZnO·Rh2O3) (Adv. Mater. 2003, 15, 1409), and it is still the only p‐type amorphous oxide to date. It was reported that an ordered structure at the nanometer scale was contained and its electronic structure is not clear yet. In this paper, optoelectronic and structural properties are reported in detail for xZnO·Rh2O3 thin films (x = 0.5–2.0) in relation to the chemical composition x. All the films exhibit positive Seebeck coefficients, confirming p‐type conduction. Local network structure strongly depends on the chemical composition. Transmission electron microscopic observations reveal that lattice‐like structures made of edge‐sharing RhO6 network exist in 2–3 nm sized grains for rhodium‐rich films (x = 0.5 and 1.0), while the zinc‐rich film (x = 2) is completely amorphous. This result indicates that excess Zn assists to form an amorphous network in the ZnO–Rh2O3 system since Zn ions tend to form corner‐sharing networks. The electronic structure of an all‐amorphous oxide p‐ZnO·Rh2O3/n‐InGaZnO4 junction is discussed with reference to electrical characteristics and results of photoelectron emission measurements, suggesting that the p/n junction has large band offsets at the conduction and valence bands, respectively.

High‐Current‐Density CuO x/InZnOx Thin‐Film Diodes for Cross‐Point Memory Applications

“…The threshold voltage seems to doubly exist at 0.8 V and 1.2 V, which agrees well with the energy gaps of 0.7 V and 1.2 V observed in optical absorption data. The diode ideality factor n was found to be 2, which is remarkably small for an oxide diode [5,12] and close to that of silicon diodes. The smaller optical bandgap feature observed in the CuO film may be related with deep-level defects near the center of the bandgap.…”

“…[5,9,12,16] The rectifying ratio was 10 6 at AE2.45 V. Figure 4b shows the J-V curve depicted in semi-logarithmic scale. The inset shows the same figure in linear scale.…”

“…If we employ a material with a bandgap energy E g,p that is larger, for example, by DE $ 1 eV, an applied voltage larger by nDE g /q is required to obtain the equal current density. Because the diode ideality factor n is reported to be 2-5 for many oxide diodes, [5,12] it corresponds to a few more volts, which obviously are a burden to practical applications.…”

Effects of Post-Deposition Annealing Atmosphere and Duration on Sol-Gel Derived Amorphous Indium-Zinc-Oxide Thin-Film Transistors

“…2. The as-deposited IZO TFTs exhibit normally-on characteristics, originating from the fact that the IZO films contain many carriers due to a relatively large nonstoichiometric chemical composition, i.e., oxygen vacancies (20,21). After the postdeposition annealing in O 2 and N 2 was performed, the device appeared to switch characteristics.…”

Function Cultivation of Transparent Oxides Utilizing Built-In Nanostructure

“…123 This material, found following our chemical design concept, 124,125 is so chemically stable that passivation is not required. This discovery is attracting attention to amorphous transparent oxide semiconductors [126][127][128][129] which has not focused. We hope that truly innovative research will cultivate a new frontier of transparent oxides as an electro-active material and lead to the realization of a sustainable society.…”