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A technique for extracting the acceptorlike density of states (DOS) of n-channel amorphous GaInZnO (a-GIZO) thin-film transistors based on the combination of subbandgap op- tical charge pumping and C-V characteristics is proposed. While the energy level is scanned by the photon energy and the gate voltage sweep, its density is extracted from the optical response of C-V characteristics. The extracted DOS shows the superpo- sition of the exponential tail states and the Gaussian deep states (NTA = 2 x 1018 eV' . cm3, NDA = 4 x iO'5 eV' . cm3, kTTA = 0.085 eV, kTDA = 0.5 eV, E0 = 1 eV). The TCAD simulation results incorporated by the extracted DOS show good agreements with the measured transfer and output characteris- tics of a-GIZO thin-film transistors with a single set of process- controlled parameters. [ABSTRACT FROM AUTHOR]

Currently, both high-density 3-D stacking nonvolatile (NV) memory and embedded NV memory in advanced systems on panel (SOPs) urgently demand the assistance of new and functional transition metal—oxide materials. This is to overcome serious fabrication issues encountered in the use of conventional Si or poly-crystalline Si materials, as well as to increase storage density with lower process cost. This paper reports the fully functional NV memory structure operated by an ionic amorphous oxide semiconductor with a wide energy band gap (> 3.0 eV) in a Ga2O3-In2O3-ZnO (GIZO) system under low process temperature (< 400 °C) while being combined with various metal-oxide materials of Al2O3, GIZO, and Al2O3 as the electron charge's tunneling, storage, and blocking layers, respectively. The different methods of memory programs and, especially, the unique erase characteristics caused by a much wider band gap than Si were intensively being investigated, and as a result, excellent electrical results of a large program/erase window over 3.8 V at a pulse time of 10 ms are achieved. [ABSTRACT FROM AUTHOR]

Amorphous Gallium-Indium-Zinc-Oxide (GIZO) thin film transistors with short channels of 50 nm were successfully fabricated by e-beam lithographic patterning. The GIZO thin film transistors showed a high mobility of 8.2 cm2/V · s with on-to-off current ratios up to 108. Excellent short channel characteristics were also obtained with a small shift of the threshold voltages and no degradation of subthreshold slopes as VDS increased, even with short channel lengths of less than 100 nm. These promising results indicate that the GIZO thin film transistors could be a candidate for selection transistors in 3-D cross point stacking memory. [ABSTRACT FROM AUTHOR]

An extraction technique for subgap density of states (DOS) in an n-channel amorphous InGaZnO thin-film transistor (TFT) by using multifrequency capacitance-voltage (C-V ) characteristics is proposed and verified by comparing the measured I-V characteristics with the technology computeraided design simulation results incorporating the extracted DOS as parameters. It takes on the superposition of exponential tail states and exponential deep states with characteristic parameters for NTA=1.1×1017 cm-3 ·eV-1, NDA=4×1015 cm-3 ·eV-1, kTTA=0.09 eV, and kTDA=0.4 eV. The proposed technique allows obtaining the frequency-independent C-V curve, which is very useful for oxide semiconductor TFT modeling and characterization, and considers the nonlinear relation between the energy level of DOS and the gate voltage VGS. In addition, it is a simple, fast, and accurate extraction method for DOS in amorphous InGaZnO TFTs without optical illumination, temperature dependence, and numerical iteration. [ABSTRACT FROM AUTHOR]

The density of states (DOS)-based DC I-V model of an amorphous gallium-indium-zinc oxide (a-GIZO) thinfilm transistor (TFT) is proposed and demonstrated with selfconsistent methodologies for extracting parameters. By combining the optical charge-pumping technique and the nonlinear relation between the surface potential (4g) and gate voltage (VGS), it is verified that the proposed DC model reproduces well both the measured VGS-dependent mobility and the IDS-VGS characteristics. Finally, the extracted DOS parameters are NTA = 4.4 x 1017 cm-3 ∙ eV-1, NDA = 3 x 1015 cm-3∙eV-1, kTTA = 0.023 eV, kTDGA = 1.5 eV, and Eo = 1.8 eV, with the formulas of exponential tail states and Gaussian deep states. [ABSTRACT FROM AUTHOR]

Abstract-The source/drain region of amorphous GaInZnO thin-film transistor with self-aligned top-gate structure was defined by simple NH[sub3] plasma treatment instead of complicated processes, such as ion implantation and activation. When the source/drain region of active layer was exposed to NH[sub3] gas plasma, the series resistance of the transistor decreased considerably. It exhibited electrical properties, such as a field-effect mobility of 6 cm[sup2]/V s, a threshold voltage of 0.21 V, and a subthreshold swing of 0.23 V/dec. [ABSTRACT FROM AUTHOR]

In this letter, we investigated the effects of source/drain series resistance on amorphous gallium-indium-doped zinc-oxide (a-GIZO) thin film transistors (TFTs). A linear least square fit of a plot of the reciprocal of channel resistance versus gate voltage yields a threshold voltage of 3.5 V and a field-effect mobility of about 13.5 cm² / V · s. Furthermore, in a-GIZO TFTs, most of the current flows in the distance range of 0-0.5 µm from the channel edge and shorter than that in a-Si:H TFTs. Moreover, unlike a-Si:H TFTs, a-GIZO TFTs did not show an intersection point, because they did not contain a highly doped ohmic (n+) layer below the source/drain electrodes. [ABSTRACT FROM AUTHOR]