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A robust ohmic contact process with ultralow contact resistivity on p-GaN/AlGaN/GaN is demonstrated. An in-situ removal of GaOX interfacial layer after contact metal deposition is developed. Using the novel Mg/Pt/Au stack as the contact metal, a stable ohmic contact is obtained after 450°C/300 s annealing with ohmic contact resistivity of $12 \Omega \cdot {\mathrm {mm}}$ ($1.8\times 10^{-5}\, \Omega \cdot {\mathrm {cm}}^{2}$). A new ohmic contact formation mechanism on p-GaN/AlGaN/GaN is also proposed. [ABSTRACT FROM AUTHOR]

A novel ohmic contact formation mechanism is revealed for the annealed Ta0.83 Al0.17/Au stacks on non-recessed i-AlGaN/GaN. It is demonstrated that the contact metal alloy mainly composed by Au penetrates the AlGaN layer without apparent Ta-related solid phase reactions, establishing a spike-free contact to the 2D electron gas. A low contact resistivity of $0.14\Omega ~\cdot $ mm (4.24E- $7~\Omega \cdot $ cm2) is then obtained after 900 °C/60s annealing. [ABSTRACT FROM AUTHOR]

A robust process for Au-free ohmic contact formation is demonstrated by a direct contact of TixAly alloy film on non-recessed i-AlGaN/GaN. Using this novel TixAly alloy instead of multilayers as contact metals, an ultra-low contact resistivity of $ < 0.1~\Omega \cdot $ mm is achieved for Ti5Al1 alloy on i-AlGaN/GaN after 880 °C/60s annealing. [ABSTRACT FROM AUTHOR]

In this paper, the ambient doping effect on negative/positive bias temperature instability (NBTI/PBTI) of single layer graphene field effect transistors (FETs) is investigated. In ambient air, the \Delta Vth of NBTI is comparable with that of PBTI under the same stress voltage at room temperature. The \Delta Vth of NBTI appears insensitive to temperature, while the \Delta Vth of PBTI increases significantly with rising temperatures, due to the thermally activated charging of ambient doped defects at the graphene/SiO2 interface. This effect also results in an abnormal recovery of NBTI. In an ambient vacuum, the \Delta Vth is much less than that in ambient air. In addition, the \Delta Vth of both NBTI and PBTI decreases substantially for higher temperatures in the vacuum. The adsorbed molecules are mainly responsible for the \Delta Vth under BTI stress and the back-gated graphene FETs in the air. [ABSTRACT FROM AUTHOR]

Large-scale rationally designed periodic Si nanopillar (SiNP) arrays of varying diameters and heights have been fabricated by a top-down method. The impacts of the structural parameters (e.g., diameter/periodicity/height) on the reflectance and absorption of the SiNP array have been extensively studied, and the results are in agreement with our theoretical prediction of Li Owing to the notably enhanced light absorption of the optimized SiNP array, a short-circuit current density Jsc of 34.3 \mA/cm^2 was obtained on an axial p-n SiNP array surface-textured solar cell, which is the highest to date among reported Si nanowire/SiNP-based solar cells. Jsc is significantly boosted compared to that of the untextured solar cell (18.1 \mA/cm^2), which implies that the SiNP array is a promising texturing technology for thin-film photovoltaic application. [ABSTRACT FROM PUBLISHER]

Inkjet-printed In-Ga-Zn oxide (IGZO) thin-film transistors (TFTs) with bottom-gate bottom-contact device architecture are studied in this paper. The impact of the IGZO film thickness on the performance of TFTs is investigated. The threshold voltage, field-effect mobility, on and off drain current, and subthreshold swing are strongly affected by the thickness of the IGZO film. With the increase in film thickness, the threshold voltage shifted from positive to negative, which is related to the depletion layer formed by the oxygen absorbed on the surface. The field-effect mobility is affected by the film surface roughness, which is thickness dependent. Our results show that there is an optimum IGZO thickness, which ensures the best TFT electrical performance. The best result is from a 55-nm-thick IGZO TFT, which showed a field-effect mobility in the saturation region of 1.41 \cm^2/\V\cdot\s, a threshold voltage of 1 V, a drain current on/off ratio of approximately \4.3 \times \10^7, a subthreshold swing of 384 mV/dec, and an off-current level lower than 1 pA. [ABSTRACT FROM AUTHOR]

In this letter, a self-compliant one-diode-one-resistor (1D1R) bipolar resistive random access memory (RRAM) has been demonstrated. By inserting a Ni/AlOy/n^+\-Si diode cell, a bipolar RRAM (TiN/HfOx/Ni) with a self-compliance current of 10 \muA is achieved. This 1D1R memory cell exhibits excellent performance, such as high ON/OFF resistance ratio (>10^2), good reproducibility and retention (>10^5~s at 100^\circC), and improved resistance distribution. And more importantly, by setting a lower SET applied voltage in the 1D1R cell, a reduced compliance current can be implemented, leading to a lower RESET voltage/current. [ABSTRACT FROM AUTHOR]

In this letter, new endurance degradation behaviors in the bipolar resistive random access memory devices with multilayered HfOx/TiOx are reported for the first time, showing almost a constant resistance in low resistance state and a gradually reduced resistance in high resistance state (HRS). Further investigations into the dependence of HRSs degradation speed on switching voltage and temperature reveal that the degradation is attributed to the oxygen ion (O^2-) loss effect during RESET process, which leads to the insufficient O^2- supply for recombining the oxygen vacancies. Possible technical solutions are then proposed to improve the endurance performance. [ABSTRACT FROM AUTHOR]

In this letter, a bipolar resistive switching RAM based on \Ni/AlOy/\n^{+}\-\Si which exhibits high potential to realize transistor-free operation for cross-bar array is successfully demonstrated. The proposed device shows well-behaved bipolar memory performance with self-rectifying behavior in low-resistance state (> 700 at 0.2 V), a high on/off resistance ratio (> \10^3), a good retention characteristic (> \10^4\ \s at 100 ^\circ\C ), and a wide readout margin for cross-bar architecture (number of word line N > \2^5 for worst case condition). [ABSTRACT FROM AUTHOR]