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

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

Results on indium-oxide-based transparent oxide TFTs, which the active layer is prepared by DC sputtering, are presented. The fabricated TOS TFTs show high mobility (37 cm2/V-s), high ON/OFF current ratio and large on-state current. Fabricating oxide TFTs on temperature-sensitive substrates is also attainable owing to the low temperature process of the active layer preparation.

15.4: Excellent Performance of Indium‐Oxide‐Based Thin‐Film Transistors by DC Sputtering

We have fabricated the transparent bottom gate TFTs using Al and Sn-doped zinc indium oxide (AT-ZIO) as an active layer. The AT-ZIO active layer was deposited by RF magnetron sputtering at room temperature, and AT-ZIO TFT showed a field effect mobility of 15.6 cm2/Vs even before annealing. The mobility increased with increasing In2O3 content and post-annealing temperature. The AT-ZIO TFT exhibited afield effect mobility of 33 cm2/Vs, a sub-threshold swing of 0.08 V/dec, and an on/off current ratio of more than 109 after Al2O3 passivation and post-annealing. We have fabricated AMOLED panels with the bottom gate AT-ZIO TFT back-plane successfully.

21.2: Al and Sn-Doped Zinc Indium Oxide Thin Film Transistors for AMOLED Back-Plane

We have fabricated transparent bottom gate thin film transistors (TFTs) using Al-doped zinc tin oxide (AZTO) as active layers. The AZTO active layer was deposited by rf magnetron sputtering at room temperature. The AZTO TFT showed good TFT performance without postannealing. The field effect mobility and the subthreshold swing were improved by postannealing below 180 °C. The AZTO TFT exhibited a field effect mobility (μFET) of 10.1 cm2/V s, a turn-on voltage (Von) of 0.4 V, a subthreshold swing (S/S) of 0.6 V/decade, and an on/off ratio (Ion/Ioff) of 109.

Transparent Al-Zn-Sn-O Thin Film Transistors Prepared at Low Temperature

We have fabricated 2.15 inch AM-OLED panel composed of 176 × 144 (106 dpi) transparent pixels driven by ZnO-TFT. Transparent ZnO thin film deposited by means of atomic layer deposition at 100°C was used for the active channel. The ZnO TFT had a mobility of 1.13cm2/V.s, a threshold voltage of 0.8V, and an on/off ratio of 106. The fabrication of the ZnO TFT array for AM-OLED display has been carried out with four-mask process. and the integration of the ZnO TFT array and the transparent OLED consisted of a transparent anode and cathode and organic layers led to really transparent display.

4.3: Transparent ZnO Thin Film Transistor Array for the Application of Transparent AM‐OLED Display

A composition for an oxide semiconductor thin film, a field effect transistor (FET) using the composition, and a method of fabricating the FET are provided. The composition includes an aluminum oxide, a zinc oxide, and a tin oxide. The thin film formed of the composition remains in amorphous phase at a temperature of 400° C or less. The FET using an active layer formed of the composition has improved electrical characteristics and can be fabricated using a low-temperature process without expensive raw materials, such as In and Ga.

Composition for oxide semiconductor thin film, field effect transistor using the composition, and method of fabricating the transistor

We investigate the effects of interfacial dielectric layers (IDLs) on the electrical properties of top-gate In-Ga-Znoxide (IGZO) thin film transistors (TFTs) fabricated at low temperatures below 200°C, using a target composition of In:Ga:Zn = 2:1:2 (atomic ratio). Using four types of TFT structures combined with such dielectric materials as Si3N4 and Al2O3, the electrical properties are analyzed. After post-annealing at 200°C for 1 hour in an O2 ambient, the sub-threshold swing is improved in all TFT types, which indicates a reduction of the interfacial trap sites. During negative-bias stress tests on TFTs with a Si3N4 IDL, the degradation sources are closely related to unstable bond states, such as Si-based broken bonds and hydrogenbased bonds. From constant-current stress tests of Id = 3 µA, an IGZO-TFT with heat-treated Si3N4 IDL shows a good stability performance, which is attributed to the compensation effect of the original charge-injection and electron-trapping behavior.

Effects of Interfacial Dielectric Layers on the Electrical Performance of Top-Gate In-Ga-Zn-Oxide Thin-Film Transistors

Provided are a thin film transistor, to which a boron-doped oxide semiconductor thin film is applied as a channel layer, and a method of fabricating the same. The thin film transistor includes source and drain electrodes, a channel layer, a gate insulating layer, and a gate electrode, which are formed on a substrate. The channel layer is an oxide semiconductor thin film doped with boron. Therefore, it is possible to remarkably improve electrical characteristics and high temperature stability of the thin film transistor.

Sung Mook Chung

Papers

Transparent Al-Zn-Sn-O Thin Film Transistors Prepared at Low Temperature

4.3: Transparent ZnO Thin Film Transistor Array for the Application of Transparent AM‐OLED Display

Composition for oxide semiconductor thin film, field effect transistor using the composition, and method of fabricating the transistor

Effects of Interfacial Dielectric Layers on the Electrical Performance of Top-Gate In-Ga-Zn-Oxide Thin-Film Transistors

Thin film transistor using boron-doped oxide semiconductor thin film and method of fabricating the same