https://iopscience.iop.org/article/10.1088/1468-6996/11/4/044305/pdf

Present status of amorphous In–Ga–Zn–O thin-film transistors

An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Semiconductor device, and manufacturing method thereof

The present invention provides a heterocyclic compound and an organic light-emitting device including the heterocyclic compound. The organic light-emitting devices using the heterocyclic compounds have high-efficiency, low driving voltage, high luminance and long lifespan.

Organic light-emitting device

Transparent amorphous oxide semiconductors have unique electron transport properties, such as large electron mobility (10–50 cm2/Vs) and the absence of a Hall voltage sign anomaly, that are not seen in conventional amorphous semiconductors. This class of materials has been attracting much attention as a channel layer in thin-film transistors (TFTs) utilizing the above features along with the processing advantage that thin films can be deposited at low temperatures by conventional sputtering methods. The primary driving force for this trend is a rapidly emerging demand for backplane TFTs that can drive the next generation of flat-panel displays. This article reviews the recent advances in fundamental science of these materials and their TFT applications. Emphasis is placed on the view that high ionicity in chemical bonding and large spherical spread of unoccupied metal s orbitals in p-block metal oxides lead to the realization of electronic structures that are advantageous for n-channel TFT applications. Amorphous oxide semiconductors are compared with conventional hydrogenated amorphous silicon, which is used widely as the channel material for backplane TFTs in current liquid-crystal displays.

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Material characteristics and applications of transparent amorphous oxide semiconductors

An object is to provide a method for manufacturing a semiconductor device, in which the number of photolithography steps can be reduced, the manufacturing process can be simplified, and manufacturing can be performed with high yield at low cost A method for manufacturing a semiconductor device includes the following steps: forming a semiconductor film; irradiating a laser beam by passing the laser beam through a photomask including a shield for shielding the laser beam; subliming a region which has been irradiated with the laser beam through a region in which the shield is not formed in the photomask in the semiconductor film; forming an island-shaped semiconductor film in such a way that a region which is not irradiated with the laser beam is not sublimed because it is a region in which the shield is formed in the photomask; forming a first electrode which is one of a source electrode and a drain electrode and a second electrode which is the other one of the source electrode and the drain electrode; forming a gate insulating film; and forming a gate electrode over the gate insulating film

Method for Manufacturing Semiconductor Device

A method for manufacturing a field-effect transistor is provided. The field-effect transistor includes on a substrate a source electrode, a drain electrode, an oxide semiconductor layer, an insulating layer and a gate electrode. The method includes, after forming the insulating layer on the oxide semiconductor layer, an annealing step of increasing the electrical conductivity of the oxide semiconductor layers by annealing in an atmosphere containing moisture. The steam pressure at the annealing step is higher than the saturated vapor pressure in the atmosphere at the annealing temperature.

Method for manufacturing field-effect transistor

This paper presents the following recent investigations of transparent amorphous-oxide semiconductors (TAOS) from materials to devices and circuits. 1) Composition of metals in TAOS are widely explored with the aim of seeking semiconductors suitable for the channel layers of thin-film transistors (TFTs) composing backplanes for flat-panel displays. It is found in combinatorial approaches to the materials exploration that indium-based ternary TAOS (In-X-O) and their TFTs show the properties and the performance as good as those of the most popular material of amorphous In-Ga-Zn-O (alpha-IGZO) when X = Zn or Ge. 2) Defects and impurities in TAOS are investigated by theoretical approaches. The first-principle calculation of the electron states reveals that charge-neutral oxygen vacancy or interstitial forms the density of states around mid-gap level and does not generate carriers directly, while hydrogen impurity raises the Fermi level beyond the conduction-band minimum and acts as a donor in TAOS. 3) Device structures of TAOS-TFTs are also investigated extensively for better performance and stability. It is found in channel-etch type TFTs with bottom-gate inverse-stagger structures that the TFT characteristics and stability are significantly improved by chemically removing the back-channel layer in a wet-etching process. Coplanar homojunction (CH) structure is proposed as a novel device structure where conductive alpha-IGZO regions work as the source and drain electrodes to the channel region of semiconductor alpha-IGZO. The CH TFTs show excellent characteristics and stability, with low series resistance without any difficulty in making good electrical contact between metals and TAOS. 4) Circuits using TAOS-TFTs are demonstrated. A ring oscillator composed of fifteen-stage inverters with a buffer circuit operates as designed by circuit simulation with a TFT model for hydrogenated amorphous Si TFTs. Pixel circuits composed of three TFTs and one transparent capacitor successfully drive organic light-emission diode cells without a planarization layer on a 2-in diagonal panel having 176 times144 times 3 pixels.

Materials, Devices, and Circuits of Transparent Amorphous-Oxide Semiconductor

There is provided a light emitting display apparatus including at least a light emitting element and a thin film transistor (TFT) for driving the light emitting element, characterized in that a mechanism is provided in which a semiconductor constituting the TFT is irradiated with at least a part of light whose wavelength is longer than a predetermined wavelength among the light emitted by the light emitting element.

Yoshinori Tateishi

Papers

Method for manufacturing field-effect transistor

Materials, Devices, and Circuits of Transparent Amorphous-Oxide Semiconductor

Light emitting display apparatus

Method for manufacturing an oxide semiconductor field-effect transistor