Abstract Transparent electronics has attracted much attention and been widely studied for next-generation high-performance flat-panel display application in the past few years, because of its excellent electrical properties. In display application, thin film transistors (TFTs) play an important role as the basic units by controlling the pixels. Among them, oxide-based TFTs have become promising candidates and gradually replaced the conventional amorphous and polycrystalline silicon TFTs, due to high mobility, good transparency, excellent uniformity and low processing temperature. Even though n-type oxide TFTs have shown high device performance and been used in commercial display application, p-type oxide TFTs with the equal performance have been rarely reported. Hence, in this paper, recent progress and challenges in p-type oxide-based TFTs are reviewed. After a short introduction, the TFT device structure and operation are presented. Then, recent developments in p-type oxide TFTs are discussed in detail, with the emphasis on the potential p-type oxide candidates as copper oxide, tin oxide and nickel oxide. Moreover, miscellaneous applications of p-type oxide TFTs are also presented. Despite this, the performance of p-type oxide TFTs still lags behind, as compared with that of n-type counterparts. Thus, the current issues and challenges of p-type oxide TFTs are briefly discussed.

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Progress and challenges in p-type oxide-based thin film transistors

High-performance vacuum-processed metal oxide thin-film transistors: A review of recent developments

Advancements for organic thin film transistors: Structures, materials, performance parameters, influencing factors, models, fabrication, reliability and applications

The development of p-type metal-oxide semiconductors (MOSs) is of increasing interest for applications in next-generation optoelectronic devices, display backplane, and low-power-consumption complementary MOS circuits. Here, we report the high performance of solution-processed, p-channel copper-tin-sulfide-gallium oxide (CTSGO) thin-film transistors (TFTs) using UV/O3 exposure. Hall effect measurement confirmed the p-type conduction of CTSGO with Hall mobility of 6.02 ± 0.50 cm2 V-1 s-1. The p-channel CTSGO TFT using UV/O3 treatment exhibited the field-effect mobility (μFE) of 1.75 ± 0.15 cm2 V-1 s-1 and an on/off current ratio (ION/IOFF) of ∼104 at a low operating voltage of -5 V. The significant enhancement in the device performance is due to the good p-type CTSGO material, smooth surface morphology, and fewer interfacial traps between the semiconductor and the Al2O3 gate insulator. Therefore, the p-channel CTSGO TFT can be applied for CMOS MOS TFT circuits for next-generation display.

High Performance of Solution-Processed Amorphous p-Channel Copper-Tin-Sulfur-Gallium Oxide Thin-Film Transistors by UV/O3 Photocuring.

Fabrication, physical modeling and dynamic response of p-type Al-doped SnOx active channel thin film transistors (TFTs) are presented for the potential application of ultra-high definition (UHD) displays. After deposition of Al-doped SnOx active layer using reactive co-sputtering, the channel was treated with plasma fluorination which improve the device performance of high ION/IOFF ratio of > 106, low subthreshold swing of ~100 mV/dec and high field-effect mobility (μFE) of 4.8 cm
 2
V
 -1
s
 -1
. To understand the origin of such high performance, physical modeling and numerical simulations were performed using density of state (DOS) model of defects/traps of oxide semiconductor. This model describes the modifications of donor-like tail states and acceptor-like Gaussian defect states due to Al doping on SnO
 x
 and fluorine treatment. To evaluate the device performance for UHD large scale displays, the dynamic responses of p-type TFT pixel circuit for various requirements are simulated with physical models. These results suggest that the Al-doped SnO
 x
 TFTs are potential candidates for future high-definition displays and many applications in transparent electronics.

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Physical Modeling of p -Type Fluorinated Al-Doped Tin-Oxide Thin Film Transistors

With experimental and numerical simulation, we report the origin of the performance enhancement in p-type SnO thin-film transistors (TFTs) due to fluorine plasma treatment (FPT). To study the effect of fluorination, using the reactive-ion-etching process, the devices are treated at various plasma powers upto 60 W. It is observed, through X-ray photoelectron spectroscopy and XRD measurements, that the plasma fluorination modifies the defect/trap states of SnO channel and SnO/HfO2 interface. These effects are introduced through density of state (DOS) model for SnO in numerical simulations, to understand the routes of electrical performance improvement. It is observed that the attributes of donor-like band-tail state and acceptor-like Gaussian defect states (Sn vacancies) are modified in overall DOS due to plasma fluorination. The treated device shows excellent electrical performances with high ${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ ratio of ~107 and low substhreshold swing of ~ 100 mV/dec and field-effect mobility ( $\mu _{\text {FE}}$ ) of 2.13 cm2V−1s−1.

Kadiyam Rajshekar

Papers

Effect of Plasma Fluorination in p-Type SnO TFTs: Experiments, Modeling, and Simulation

Physical Modeling of p -Type Fluorinated Al-Doped Tin-Oxide Thin Film Transistors

Modeling of Field Dependent Maxwell-Wagner Interfacial Capacitance for Bilayer Metal-Insulator-Metal (MIM) Capacitors