We have investigated the gate-voltage dependence and the temperature dependence of the magnetoconductivity of amorphous indium-gallium-zinc-oxide thin-film transistors. A weak-localization feature is observed at small magnetic fields on top of an overall negative magnetoconductivity at higher fields. An intriguing controllable competition between weak localization and weak antilocalization is observed by tuning the gate voltage or varying the temperature. Our findings reflect controllable quantum interference competition in the electron systems in amorphous indiumgallium-zinc-oxide thin-film transistors.Amorphous metal-oxide semiconductors have recently been studied for applications in thin-film transistors (TFTs) for large-area flexible electronics because of their electrical uniformity and fabrication advantage of roomtemperature deposition and patterning [1][2][3][4]. In particular, zinc oxide (ZnO) has recently attracted intense experimental and theoretical attention owing to its potential use in the emerging nanoelectronics and optoelectronics [5][6][7]. ZnO-based semiconductors can incorporate indium oxide as a carrier-mobility enhancer and gallium oxide or hafnium oxide as a columnar-structure suppressor for the amorphous phase in order to achieve high field-effect mobility and low off-state current of the channel [8][9][10]. They have become promising candidates of transparent and flexible nonvolatile memories to be integrated in system-on-panel displays [11][12][13].Aside from practical studies to achieve higher quality of amorphous indium-gallium-zinc-oxide (InGaZnO 4 ) TFTs, investigations of their fundamental electrical properties at low temperatures are necessary for studying quantum corrections to the conductivities of these carrier systems with disorders. Quantum interference and weak localization have been explored in three-dimensional and low-dimensional electron systems in various materials [14][15][16][17][18][19][20][21]. Indium zinc oxide (IZO) films and nanowires [22][23][24][25][26][27] in particular have raised special interest because of their potential applications in modern technologies. However, a comprehensive, in-depth study of lowtemperature electrical transport in IZO is still missing, and the underlying mesoscopic and microscopic mechanisms remain largely unclear. Moreover, there are few detailed studies of low-temperature transport properties of practical IZO transistor devices. Measurements of IZO * E-mail: pjiang@ntnu.edu.tw transistors at low temperatures may reveal interesting quantum-mechanical phenomena.In this work, we present a study of the drain-source channel magnetoconductivity (MC) of an amorphous InGaZnO 4 (a-IGZO) TFT measured at cryogenic temperatures. Manipulated via electric gating, the MC reveals a competition between weak localization (WL) and weak antilocalization (WAL) at small magnetic fields, where the WL component stays small but steady, while the WAL component lessens drastically with decreasing gate voltage. On the other hand, the temperature dependence...

This work demonstrates the generation of abnormal capacitance for amorphous indium-gallium-zinc oxide (a-InGaZnO4) thin-film transistors after being subjected to negative bias stress under ultraviolet light illumination stress (NBIS). At various operation frequencies, there are two-step tendencies in their capacitance-voltage curves. When gate bias is smaller than threshold voltage, the measured capacitance is dominated by interface defects. Conversely, the measured capacitance is dominated by oxygen vacancies when gate bias is larger than threshold voltage. The impact of these interface defects and oxygen vacancies on capacitance-voltage curves is verified by TCAD simulation software.

This Letter investigates a hump in gate current after negative-bias temperature-instability (NBTI) in HfO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors. Measuring gate current at initial through body floating and source/drain floating shows that hole current flows from source/drain. The fitting of gate current (Ig)-gate voltage (Vg) characteristic curves demonstrates that the Frenkel-Poole mechanism dominates the conduction. Next, by fitting the gate current after NBTI, in the order of Frenkel-Poole then tunneling, the Frenkel-Poole mechanism can be confirmed. These phenomena can be attributed to hole trapping in high-k bulk and the electric field formula Ehigh-k εhigh-k = Q + Esio2εsio2.

In this paper, amorphous InGaZnO 4 thin-film transistors with an asymmetric structure exhibit ultraviolet (UV) light sensing property. At the offset region near the drain electrode, the extended active layer plays the role of a resistor. However, the ON-state current is obviously reduced with increasing offset length at the offset region near the source electrode and the characteristics cannot be turned ON when offset length is over 4 µm. After exposure to UV light, photogenerated holes-induce source barrier lowering and then amplifying the photocurrent response. Therefore, the devices in this paper reach a high-ON/OFF ratio of UV sensitivity to 10 6 .

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