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A metallic-target reactive co-sputtering technology is used to fabricate zinc tin oxide (ZTO) thin-film transistors (TFTs). The effect of the O2/(Ar+O2) flow rate ratio on the performance of the resulting TFTs is investigated in detail. It is found that an O2/(Ar+O2) ratio of 11%–12% produces devices with the best performance, including a linear mobility of 8.6 cm2/Vs, subthreshold swing of 0.36 V/decade,...
Various thicknesses (0, 5 and 70 nm) TiO2:Nb (TNO) films are used for the fabrication of amorphous InGaZnO (a-IGZO) thin film transistors (TFTs) with Mo/TNO source-drain (S-D) electrodes. All the as-prepared TFTs show similar electrical performance. However, the on-current of a-IGZO TFT with Mo/TNO(5 nm) S-D electrodes decreases dramatically after 300 °C annealing due to the large S-D parasitic resistance...
A power-on-reset (POR) circuit, which is an important block in mixed-signal integrated circuits, is used for the correct initialization of critical logic states in digital blocks of mixed-signal circuits. A POR circuit with precisely triggered threshold voltages is proposed. The circuit is designed in a 0.18 μm CMOS technology with a maximum 4 μA quiescent current. The output signal of the proposed...
A 27.6 MHz 297 μW relaxation oscillator is presented in this paper by using an 180-nm CMOS technology. The proposed oscillator employs an adjustable temperature compensation feedforward scheme, in which the charging current can be set steady by a four-bit digital trimming signal. We have demonstrated a frequency variation lower than 33.5 ppm/°C which could be close to 0 ppm/°C in theory if the precision...
Based on the Meyer-Neldel Rule (MNR), analytical drain current model is presented for the polycrystalline ZnO thin-film transistors at different temperatures. The MNR-based drain current model is developed from the surface-potential-based model considering the effective medium approximation (EMA). Applying the Meyer-Neldel Rule, the drain current model is developed. The model results are in agreement...
In this paper, we consider the problem of event prediction with multi-variate time series data consisting of heterogeneous (continuous and categorical) variables. The complex dependencies between the variables combined with asynchronicity and sparsity of the data makes the event prediction problem particularly challenging. Most state-of-art approaches address this either by designing hand-engineered...
We proposed and fabricated amorphous indium-gallium-zinc-oxide thin-film transistors (IGZO TFTs) employing a novel organic-passivation layer (1-Methoxy-2-Propanol positive resist). The 1-Methoxy-2-Propanol passivated TFTs exhibit almost non-degraded electrical properties with carrier mobility, subthreshold swing of 5.9 cm2/Vs, 0.38 V/dec, respectively compared to the unpassivated TFTs. Besides, the...
Zinc oxide is a well-known wide band gap semiconductor material which can be applied to thin film transistors. Al-doped ZnO (AZO) has a better electrical conductivity than Zinc oxide at the same time with good photoelectric properties. In this paper, the method of atomic layer deposition (ALD) was used to prepare the ZnO and Al:ZnO (AZO) thin films as the active layers on silicon substrates at 100...
As a basic block of carbon materials with different dimensions, graphene has shown great potential in novel device field. As a result, it becomes extremely important to break the zero-band-gap status of graphene sheet. In this work, the density functional theory (DFT) has been carried out to calculate the electronic structure of La-doped monolayer graphene under both X-direction uniaxial and Y-direction...
In this paper, we propose a floating high-voltage level shifter without static power consumption which is used in a pre-charge circuit for large-size active matrix organic light-emitting diode (AMOLED) displays. The proposed level shifter is a high voltage tolerant level shifter with only middle-voltage transistors which operate within the voltage limits. No high-voltage transistors make it occupy...
Simple drain current and 1/f noise expressions are presented for polycrystalline silicon (poly-Si) thin-film transistors (TFTs) in leakage regime. The leakage current expression Ids is derived from the thermal field emission mechanism. The leakage current noise power spectral density (PSD) expression SIds is derived from the carrier number fluctuation theory. It is proved that SIds is proportional...
Zinc tin oxide (ZTO) thin film transistors (TFTs) with back-channel-etch (BCE) structure are demonstrated. The influence of oxygen partial pressure during ZTO layer sputtering is discussed and an optimal O2/Ar ratio of 1% is achieved. The effect of annealing temperature is studied and the device annealed at 300°C performs well. The wet etching of Mo source/drain electrodes is carried out in Mo etchant...
The influence of substrate bias during sputtering on the amorphous indium-gallium-zinc-oxide (a-IGZO) film and back-channel-etch (BCE) a-IGZO TFT is investigated. A mediated substrate bias is benefit to the improvement of a-IGZO film. The BCE a-IGZO TFT with mediate substrate bias of −90 V exhibits good performances with a field effect mobility (μfe) of 7.45 cm2/V·s, a subthreshold swing (SS) of 0...
In this work, we study threshold voltage (Vth) shift degradation in amorphous IGZO (a-IGZO) TFTs. The TFTs employ the bottom-gate staggered structure with an etch stopped layer. An improvement is presented to well known stretched-exponential equation for the Vth shift, and a systematic extraction method is provided. The Vth shift in a-IGZO TFTs is estimated quantitatively under different gate bias...
Aqueous ammonia is used as the new additive to the H2O2-based etchant for back-channel-etch (BCE) amorphous Indium gallium zinc oxide (a-IGZO) thin-film transistors (TFTs) to pattern Mo source/drain. The Mo residue after being etched by H2O2:NH3·H2O is removed completely by adjusting the PH value to above 7. The BCE a-IGZO TFTs fabricated with the new solution exhibit excellent performances with the...
We propose a self-aligned top-gate amorphous InGaZnO thin film transistor (a-IGZO TFT) with source/drain treated by N2 plasma. By comparing the performances of the self-aligned top-gate a-IGZO TFTs with N2 and Ar plasma treatment, it is found that N2 plasma treatment can effectively decrease the resistivity of the a-IGZO. The TFTs with N2 plasma treated source/drain have the comparable electrical...
This work presents a new pixel circuit and driving scheme for active-matrix organic light-emitting diode (AMOLED) displays, where the OLED is under AC bias. The proposed pixel circuit consists of five thin film transistors (TFTs) and one capacitor. Due to the AC bias, the OLED is reverse biased during the non-emission period, which not only prevents the OLED from light emitting during the programming...
The 1/f noise characteristics are analyzed for the polycrystalline silicon (poly-Si) thin-film transistors (TFTs) in both subthreshold regime and above-threshold regime. Based on carrier number fluctuation model, our previous 1/f noise model for the amorphous InGaZnO TFTs is applied to the poly-Si TFTs considering mobility power-law parameter. The mobility power-law parameter determines the relationship...
Fully-transparent Mo-doped ZnO (MZO) thin film transistors (TFTs) have been successfully fabricated on glass substrate by radio frequency Magnetron Sputtering at room temperature and its characteristics have been studied in different oxygen partial pressure. The results show that the MZO TFTs which were deposited at low oxygen partial pressure (10%) have excellent performance such as subthreshold...
Dry-etch for patterning Mo source/drain electrodes directly on amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistors (TFTs) with back-channel-etch (BCE) structure was investigated. The over-etching time of reactive ion etching (RIE) had a great influence on the performance of the BCE a-IGZO TFTs. The a-IGZO TFTs with an appropriate over-etching time, such as 20s, was observed with a field...
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