Transparent Al–Zn–Sn–O thin film transistors prepared at low temperature

Abstract

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.

Overview of electroceramic materials for oxide semiconductor thin film transistors

“…Therefore, the role of the carrier-suppressor appears to influence carrier concentration, Hall mobility, and device stability due to its high oxygen-bonding ability. Cost-efficient ZnSnO-matrix-based oxide semiconductors have been under investigation with the addition of a variety of carrier-suppressors due to the high-cost and scarcity of indium and gallium [47,51]. Cho et al [51] reported an amorphous AlZnSnO TFT, that exhibited μ fe of 10.1 cm 2 /V · s, S of 0.6 V/ decade, and drain current on/off ratio of 10 9 after annealing at 180°C.…”

“…Cost-efficient ZnSnO-matrix-based oxide semiconductors have been under investigation with the addition of a variety of carrier-suppressors due to the high-cost and scarcity of indium and gallium [47,51]. Cho et al [51] reported an amorphous AlZnSnO TFT, that exhibited μ fe of 10.1 cm 2 /V · s, S of 0.6 V/ decade, and drain current on/off ratio of 10 9 after annealing at 180°C. Later, Fortunato et al [52] developed an amorphous GaSnZnO channel layer, produced by rf magnetron cosputtering using gallium zinc oxide (GZO) and tin (Sn) targets.…”

“…The researchers suggested that high postannealing (300°C) treatment of a-GaSnZnO TFTs produced better electrical performance and stability than those of a-IGZO TFTs due to the Ga 3+ and Sn 4+ ions. There have been many similar demonstrations to date involving Si, Al, Zr, Hf, Ga, and Sn with InZnO and ZnSnO matrices, aimed at improving electrical performance (e.g., μ fe and stability) [38][39][40][41][42][43][44][45][46][47][48][49][50][51][52].…”

The Characteristics of Amorphous-Oxide-Semiconductor Thin-Film-Transistors According to the Active-Layer Structure

“…Continuous research on oxide-semiconductor thin-film-transistors (OS-TFTs) has resulted in initial characteristics that are superior to those of a-Si; however, their long-term stability is still a problem to be overcome [9,10]. Recently, oxide semiconductors without indium have attracted attention because indium is becoming more expensive [11,12]. AMOLED prototypes using OS-TFTs have been developed by a few manufacturers.…”

A protective layer on the active layer of Al‐Zn‐Sn‐O thin‐film transistors for transparent AMOLEDs

“…Oxide TFTs with an active layer composed of Al 2 O 3 -ZnO-SnO 2 (AZTO) and sputtered at room temperature have been reported by these researchers. [12] The AZTO material is very stable chemically, and the sputtering method has the advantages of low cost and large-area uniformity among the various existing deposition methods. Therefore, the AZTO TFT is a prominent device for driving the large-size AMOLED panel.…”