The compelling demand for higher performance and lower power consumption in electronic systems is the main driving force of the electronics industry's quest for devices and/or architectures based on new materials. Here, we provide a review of electronic devices based on two-dimensional materials, outlining their potential as a technological option beyond scaled complementary metal-oxide-semiconductor switches. We focus on the performance limits and advantages of these materials and associated technologies, when exploited for both digital and analog applications, focusing on the main figures of merit needed to meet industry requirements. We also discuss the use of two-dimensional materials as an enabling factor for flexible electronics and provide our perspectives on future developments.

Electronics based on two-dimensional materials

Transparent electronics is today one of the most advanced topics for a wide range of device applications. The key components are wide bandgap semiconductors, where oxides of different origins play an important role, not only as passive component but also as active component, similar to what is observed in conventional semiconductors like silicon. Transparent electronics has gained special attention during the last few years and is today established as one of the most promising technologies for leading the next generation of flat panel display due to its excellent electronic performance. In this paper the recent progress in n- and p-type oxide based thin-film transistors (TFT) is reviewed, with special emphasis on solution-processed and p-type, and the major milestones already achieved with this emerging and very promising technology are summarizeed. After a short introduction where the main advantages of these semiconductors are presented, as well as the industry expectations, the beautiful history of TFTs is revisited, including the main landmarks in the last 80 years, finishing by referring to some papers that have played an important role in shaping transparent electronics. Then, an overview is presented of state of the art n-type TFTs processed by physical vapour deposition methods, and finally one of the most exciting, promising, and low cost but powerful technologies is discussed: solution-processed oxide TFTs. Moreover, a more detailed focus analysis will be given concerning p-type oxide TFTs, mainly centred on two of the most promising semiconductor candidates: copper oxide and tin oxide. The most recent data related to the production of complementary metal oxide semiconductor (CMOS) devices based on n- and p-type oxide TFT is also be presented. The last topic of this review is devoted to some emerging applications, finalizing with the main conclusions. Related work that originated at CENIMAT|I3N during the last six years is included in more detail, which has led to the fabrication of high performance n- and p-type oxide transistors as well as the fabrication of CMOS devices with and on paper.

Oxide Semiconductor Thin‐Film Transistors: A Review of Recent Advances

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 effect of water exposure on amorphous indium-gallium-zinc oxide (a-IGZO) semiconductors was reported. It was found that water can diffuse in and out of the a-IGZO film, reversibly affecting the transistor properties. Two competing mechanisms depending on the thickness of the active channel were clarified. The electron donation effect caused by water adsorption dominated for the thicker a-IGZO films (⩾100nm), which was manifested in the large negative shift (>14V) of the threshold voltage. However, in the case of the thinner a-IGZO films (⩽70nm), the dominance of the water-induced acceptorlike trap behavior was observed. The direct evidence for this behavior was that the subthreshold swing was greatly deteriorated from 0.18V/decade (before water exposure) to 4.4V/decade (after water exposure) for the thinnest a-IGZO films (30nm). These results can be well explained by the screening effect of the intrinsic bulk traps of the a-IGZO semiconductor.

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Electronic transport properties of amorphous indium-gallium-zinc oxide semiconductor upon exposure to water

The effect of Ar plasma treatment on amorphous indium gallium zinc oxide (a-IGZO) thin films was investigated The net electron carrier concentration (1020–1021cm−3) of the a-IGZO thin films dramatically increased upon their exposure to the Ar plasma compared to that (1014cm−3) of the as-deposited thin film The authors attempted to reduce the contact resistance between the Pt∕Ti (source/drain electrode) and a-IGZO (channel) by using the Ar plasma treatment Without the treatment, the a-IGZO thin film transistors (TFTs) with W∕L=50∕4μm exhibited a moderate field-effect mobility (μFE) of 33cm2∕Vs, subthreshold gate swing (S) of 025V∕decade, and Ion∕off ratio of 4×107 The device performance of the a-IGZO TFTs was significantly improved by the Ar plasma treatment As a result, an excellent S value of 019V∕decade and high Ion∕off ratio of 1×108, as well as a high μFE of 91cm2∕Vs, were achieved for the treated a-IGZO TFTs

Improvements in the device characteristics of amorphous indium gallium zinc oxide thin-film transistors by Ar plasma treatment

The full color 121-inch WXGA active-matrix organic light emitting diode (AMOLED) display was, for the first time, demonstrated using indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs) as an active-matrix back plane It was found that the fabricated AMOLED display did not suffer from the well-known pixel non-uniformity of luminance, even though the simple structure consisting of 2 transistors and 1 capacitor was adopted as a unit pixel circuit, which was attributed to the amorphous nature of IGZO semiconductor The n-channel a-IGZO TFTs exhibited the field-effect mobility of 82 cm2/Vs, threshold voltage of 11 V, on/off ratio of > 108, and subthreshold gate swing of 058 V/decade The AMOLED display with a-IGZO TFT array would be promising for large size applications such as note PC and HDTV because a-IGZO semiconductor can be deposited on large glass substrate (> Gen 7) using conventional sputtering system

3.1: Distinguished Paper: 12.1-Inch WXGA AMOLED Display Driven by Indium-Gallium-Zinc Oxide TFTs Array

Disclosed is a thin film transistor including a P-type semiconductor layer, and an organic light-emitting display device having the thin film transistor. The present invention provides a thin film transistor including a substrate, a semiconductor layer, and a gate electrode and a source/drain electrode formed on the substrate, wherein the semiconductor layer is composed of P-type ZnO:N layers through a reaction of a mono-nitrogen gas with a zinc precursor, and the ZnO:N layer includes an un-reacted impurity element at a content of 3 at % or less.

Thin film transistor and organic light-emitting display device having the thin film transistor

An Organic Light Emitting Display (OLED) and a method of fabricating the OLED includes: a substrate including a pixel region and a non-pixel region; a gate electrode arranged in the non-pixel region of the substrate; a first insulating layer arranged on the substrate having the gate electrode formed thereon, and having an open groove on an upper surface of a region opposite to the gate electrode; a semiconductor layer buried in the groove and including a source region, a channel region and a drain region; and an organic thin film layer arranged in the pixel region of the substrate. A common electrode is arranged between the drain region of the semiconductor layer and the organic thin film layer to electrically couple the drain region to the organic thin film layer.

Yeon-Gon Mo

Papers

Electronic transport properties of amorphous indium-gallium-zinc oxide semiconductor upon exposure to water

Improvements in the device characteristics of amorphous indium gallium zinc oxide thin-film transistors by Ar plasma treatment

3.1: Distinguished Paper: 12.1-Inch WXGA AMOLED Display Driven by Indium-Gallium-Zinc Oxide TFTs Array

Thin film transistor and organic light-emitting display device having the thin film transistor

Organic light emitting display (OLED) and its method of fabrication