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This paper presents a comprehensive investigation into the DC analog and AC microwave performance of a state-of-the-art T-gate double barrier AlGaN/AlInGaN/GaN MOSHEMT (Metal Oxide Semiconductor High Electron Mobility Transistor) implemented on a 4H-SiC substrate. The study involves meticulous numerical simulations and an extensive comparison with a single barrier design, utilizing the TCAD-Silvaco software. The observed disparity in performance can be attributed to the utilization of double barrier technology, which enhances electron confinement and current density by augmenting the polarization-induced charge during high-frequency operations. Remarkably, when compared to the single barrier design, the double barrier MOSHEMT exhibits a notable 15% increase in drain current, a 5% increase in transconductance, and an elevated breakdown voltage (VBR) of 140 V in E-mode operation. Furthermore, the radio frequency analysis of the double barrier device showcases exceptional performance, setting new records with a maximum oscillation frequency (fmax) of 1.148 THz and a gain cutoff frequency (ft) of 891 GHz. These impressive results obtained through deck-simulation affirm the immense potential of the proposed double barrier AlGaN/AlInGaN/GaN MOSHEMT for future applications in high-power and terahertz frequency domains.

Purpose – The purpose of this paper is to show the existence results for adapted solutions of infinite horizon doubly reflected backward stochastic differential equations with jumps. These results are applied to get the existence of an optimal impulse control strategy for an infinite horizon impulse control problem. Design/methodology/approach – The main methods used to achieve the objectives of this paper are the properties of the Snell envelope which reduce the problem of impulse control to the existence of a pair of right continuous left limited processes. Some numerical results are provided to show the main results. Findings – In this paper, the authors found the existence of a couple of processes via the notion of doubly reflected backward stochastic differential equation to prove the existence of an optimal strategy which maximizes the expected profit of a firm in an infinite horizon problem with jumps. Originality/value – In this paper, the authors found new tools in stochastic analysis. They extend to the infinite horizon case the results of doubly reflected backward stochastic differential equations with jumps. Then the authors prove the existence of processes using Envelope Snell to find an optimal strategy of our control problem.

A novel lattice matched double barrier Al0.72In0.16Ga0.12N/Al0.18In0.04Ga0.78N/GaN normally-off high electron mobility transistor (HEMT) is designed and simulated by solving a set of thermodynamic transport equations. Using the experimentally calibrated physical models with bearing mobility degradation by surface roughness in account, the recess gate and double barrier of the proposed device achieves a maximum drain current density (ID,max) of 1149 mA/mm and a maximum transconductance (gD,max) of 358 mS/mm with a positive threshold voltage (Vth) of 0.2 V. The small polarization charge of first barrier is responsible for positive Vth. IDS,max in the double barrier HEMT at high gate bias condition is due to injection of electrons from upper 2DEG which is almost impossible at lower gate voltage because of insufficient energy to cross the barrier. The injection of electrons is further supported by the second peak in the gm curve at low gate bias VG = 1V. The outcome of this study suggests that the proposed device will be beneficial for high-frequency and high-power electronic applications.

In this paper, we apply an improved version of Monte Carlo methods to pricing barrier options. This kind of options may match with risk hedging needs more closely than standard options. Barrier options behave like a plain vanilla option with one exception. A zero payoff may occur before expiry, if the option ceases to exist; accordingly, barrier options are cheaper than similar standard vanilla options. We apply a new Monte Carlo method to compute the prices of single and double barrier options written on stocks. The basic idea of the new method is to use uniformly distributed random numbers and an exit probability in order to perform a robust estimation of the first time the stock price hits the barrier. Using uniformly distributed random numbers decreases the estimation of first hitting time error in comparison with standard Monte Carlo or similar methods. It is numerically shown that the answer of our method is closer to the exact value and the first hitting time error is reduced.

Abstract. The application of double barrier (DB) structure in p-i-n amorphous silicon (a-Si) device was studied. The theoretical study was done to obtain device parameters such as tunneling probability and current density. The tunneling probability was calculated by employing the Schroedinger equation, WKB approximation and Green function. Width of potential well, width and height of barrier were varied to obtain the highest tunneling probability value. The current density was contributed by diffusion, and tunneling current densities. It was found that current density had a peak of 3950 A/m2 at 0.56 volt forward bias. Furthermore, the fabrication of p-i-n a-Si device with double barrier structure was successfully carried out. To realize the double barrier structure, optimization of optical band gap of barrier a-SiC:H was done by varying ratio of CH4 to [CH4+SiH4]. The fabrication of p-i-n a-Si device was then done by using Plasma Enhanced Chemical Vapor Deposition (PECVD) technique with a structure of glass substrate/TCO/p-a-Si:H (2.15 eV;140Ã…)/i-a-Si:H (1.81 eV;1800 Ã…)/barrier a-SiC:H (2.36 eV;45 Ã…)/potential well i-a-Si:H (1/81 eV; 30 Ã…)/barrier a-SiC:H (2.36 eV; 45 Ã…)/n-a-Si:H (1.81 eV;180 Ã…)/Al. The I-V characteristic of the device showed a peak current calue at 0.55 forward bias. Simulasi dan Fabrikasi Struktur Double Barrier pada Divais Amorphous Silicon Sari. Aplikasi struktur double barrier (DB) pada divais amorphous silicon (a-Si) telah dilakukan untuk memperoleh beberapa parameter divais seperti probabilitas tunneling dan rapat arus. Probabilitas tunneling dihitung dengan menerapkan persamaan Schroedinger, pendekatan WKB dan fungsi Green. Lebar sumur potensial, lebar dan tinggi barrier telah divariasikan untuk memperoleh harga probabilitas tunneling yang maksimum. Rapat arus total dari divais dalam perhitungan ini merupakan jumlah dari rapat arus difusi dan rapat arus tunneling. Diperoleh bahwa rapat arus total memiliki nilai maksimum sebesar 3950 A/m2 pada tegangan bias maju 0,56 volt. Selanjutnya, telah berhasil juga difabrikasi divais p-i-n a-Si dengan struktur double barrier. Didapatkan bahwa karakteristik I-V dari divais menunjukkan adanya puncak rapat arus pada tegangan bias maju 0,55 volt. ihamidah@eudoramail.com

In this work, recessed gate AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) with double AlGaN barrier designs are fabricated and investigated. Two different recessed depths are designed, leading to a 5 nm and a 3 nm remaining bottom AlGaN barrier under the gate region, and two different Al% (15% and 20%) in the bottom AlGaN barriers are designed. First of all, a double hump trans-conductance (gm)−gate voltage (VG) characteristic is observed in a recessed gate AlGaN/GaN MIS-HEMT with a 5 nm remaining bottom Al0.2Ga0.8N barrier under the gate region. Secondly, a physical model is proposed to explain this double channel characteristic by means of a formation of a top channel below the gate dielectric under a positive VG. Finally, the impacts of Al% content (15% and 20%) in the bottom AlGaN barrier and 5 nm/3 nm remaining bottom AlGaN barriers under the gate region are studied in detail, indicating that lowering Al% content in the bottom can increase the threshold voltage (VTH) toward an enhancement-mode characteristic.