Leakage mechanism in AlxGa1-xN/GaN heterostructures with AlN interlayer

Leakage of AlxGa1-xN/GaN heterostructures was investigated by admittance–voltage profiling. Nominally undoped structures were grown by low-pressure metal-organic vapor-phase epitaxy (MOVPE). The investigated structures had an Al-content of 30 %. They are compared to structures with an additional 1 nm thick AlN interlayer placed before the Al0.3Ga0.7N layer growth, originally to improve device performance. Conductance of FET devices with AlN interlayer, measured from depletion of the two-dimensional electron gas (2DEG) to zero volt bias at frequencies ranging from 50 Hz to 10 kHz, could be described by free charge carriers using a Drude model. The voltage dependent conductance shows a behavior described by either Poole-Frenkel emission or Schottky emission. From the size of the conductance, as well as simulation of the tunneling current injected from the gate under off-state conditions by universal Schottky tunnelling, Schottky Emission is obvious. Evaluating the data by Schottky emission, we can locate the leakage path, of tens of nm in the range between gate and drain/source with contact to the 2DEG, originating from the AlN interlayer. The static dielectric constant in growth direction, necessary for the evaluation, is determined from various AlxGa1 xN/GaN heterostructures to ε||(0) = 10.7 +/- 0.1.

FIN Junctionless Field Effect Transistor (FIN-JLFET) With Ground Plane For Surpassing Parasitic BJT Action

The leakage mechanism due to lateral band-to-band tunneling (L-BTBT) results in increased off state current and hinders the scaling of the junctionless transistor. The effect of L-BTBT on FIN shaped gate Junctionless field effect transistor (JLFET) with the ground plane (GP) in oxide has been investigated. The proposed device is simulated using 3-D Silvaco TCAD and shows that it can mitigate the L-BTBT and leads to efficient volume depletion which relaxes the requirements of ultra-thin silicon thickness and high workfunction of the gate electrode. The results show significantly reduced OFF-state current and high Ion /Ioff ratio even at scaled gate length beyond 10 nm along with the reduction in drain induced barrier lowering and threshold voltage roll-off . Thus, the proposed device shows better performance at sub-10 nm node.

Failure-based sealing reliability analysis considering dynamic interval and hybrid uncertainties

In the reliability analysis of a sealing structure, radial clearance of the contact surface is usually regarded as a failure criterion, and the sample size is usually quite small, which brings great challenges to uncertainty quantification. Therefore, this paper proposes a reliability analysis method based on the leakage mechanism of the sealing. With the application of dynamic interval, the proposed method can be used to deal with problem of degradation in small sample to evaluate reliability. Moreover, the dynamic reliability with the mixture of the probabilistic and non-probabilistic variables can be obtained using the proposed method. An illustrative numerical case study of a spool valve is conducted in order to validate the proposed method and the implemented reliability sensitivity analysis. The proposed method is of great help in evaluating and predicting reliability with small degradation sample and hybrid uncertainties.

Failure-based sealing reliability analysis considering dynamic interval and hybrid uncertainties

In the reliability analysis of a sealing structure, radial clearance of the contact surface is usually regarded as a failure criterion, and the sample size is usually quite small, which brings great challenges to uncertainty quantification. Therefore, this paper proposes a reliability analysis method based on the leakage mechanism of the sealing. With the application of dynamic interval, the proposed method can be used to deal with problem of degradation in small sample to evaluate reliability. Moreover, the dynamic reliability with the mixture of the probabilistic and non-probabilistic variables can be obtained using the proposed method. An illustrative numerical case study of a spool valve is conducted in order to validate the proposed method and the implemented reliability sensitivity analysis. The proposed method is of great help in evaluating and predicting reliability with small degradation sample and hybrid uncertainties.

High Curie Temperature BiFeO3-BaTiO3 Lead-free Piezoelectric Ceramics: Ga3+ Doping and Enhanced Insulation Properties

BiFeO3-BaTiO3 (BF-BT) is a promising high temperature lead-free piezoceramics due to their excellent piezoelectric properties with high Curie temperature (TC>500 °C). While the high leakage current density severely restricted its application. In this work, the leakage mechanism relative to the dielectric properties and piezoelectric properties were systematically studied with a special emphasis on gallium (Ga3+) adding effect in 0.7BiFe(1-x)GaxO3-0.3BaTiO3 (BFGax-BT, 0≤x≤0.10) ceramics. A high resistivity (ρ) of 2.73×1012 Ω·cm-1 and low leakage current (J) of 7.78×10-9 A·cm-2 were achieved at x=0.06, which attributes to the low oxygen vacancies (B). The J-E curves reveal different type of conduction process in BFGax-BT ceramics, including Ohmic conduction, space-charge-limited conduction (SCLC) mechanism and interface-limited Schottky emission. The BFGa0.06-BT ceramic exhibits excellent piezoelectric performance: d33=174 pC·N-1, TC=497 °C, kp=29 %.