High-Performance InGaAs HEMTs on Si Substrates for RF Applications

In this paper, we have fabricated InGaAs high-electron-mobility transistors (HEMTs) on Si substrates. The InAlAs/InGaAs heterostructures were initially grown on InP substrates by molecular beam epitaxy (MBE), and the adhesive wafer bonding technique was employed to bond the InP substrates to Si substrates, thereby forming high-quality InGaAs channel on Si. The 120 nm gate length device shows a maximum drain current (ID,max) of 569 mA/mm, and the maximum extrinsic transconductance (gm,max) of 1112 mS/mm. The current gain cutoff frequency (fT) is as high as 273 GHz and the maximum oscillation frequency (fMAX) reaches 290 GHz. To the best of our knowledge, the gm,max and the fT of our device are the highest ever reported in InGaAs channel HEMTs on Si substrates at given gate length above 100 nm.

Investigation of turn-on performance in 1.2-kV MOS-bipolar devices

In this paper, the turn-on characteristics of 1.2-kV Trench IGBT (TIGBT) and Trench Clustered IGBT (TCIGBT) are investigated through TCAD simulations and experiments. TCIGBT shows much lower turn-on energy loss (Eon) due to higher current gain than an equivalent TIGBT and the negative gate capacitance effect is effectively suppressed in the TCIGBT by its self-clamping feature and PMOS action. In addition, the impact of 3-D scaling rules on the turn-on performance of TIGBT and TCIGBT is analyzed in detail. Simulation results show that scaling rules result in a significant reduction of Eon in both TIGBT and TCIGBT. Furthermore, the experimental results indicate that TCIGBT technology is well suited for high current density operations with low power losses. Compared to the state-of-the-art IGBT technology, an 18 % reduction of total power losses can be achieved by the TCIGBT operated at 300 A/cm2 and 175 °C.

Strain-engineering in AlGaN/GaN HEMTs: impact of silicon nitride passivation layer on electrical performance

In this work, we present a physics-based analysis of two-dimensional electron gas (2DEG) sheet carrier density and other microwave characteristics such as transconductance and cutoff frequency of AlxGa1-xN/GaN high electron mobility transistors (HEMT). An accurate polarization-dependent charge control-based analysis is performed for microwave performance assessment in terms of current, transconductance, gate capacitances, and cutoff frequency of lattice-mismatched AlGaN/GaN HEMTs. The influence of stress on spontaneous and piezoelectric polarization is included in the simulation of an AlGaN/GaN HEMT. We have shown the change in threshold voltage (Vt) due to tensile and compressive strain with different gate lengths. Also, the influence of stress due to the change in nitride thickness is presented. Our simulation results for drain current, transconductance, and current-gain cutoff frequency for various gate length devices are calibrated and verified with experimental data over a wide range of gate and drain applied voltages, which are expected to be useful for microwave circuit design. The predicted transconductance, drain conductance, and operation frequency are quite close to the experimental data. The AlGaN/GaN heterostructure HEMTs with nitride passivation layers show great promise as a candidate in future high speed and high power applications.

Study of characteristics of n-p-n type bipolar power transistor in small-sized metalpolymeric package type SOT-89

In this study the input, output and current gain characteristics of silicon n-p-n type medium power bipolar junction transistors KT242A91 made by the "GRUPPA KREMNY EL" in modern small-sized metalpolymeric package type (SOT-89) have been obtained. The SPICE model that allows simulating realistic transistor behaviour of n-p-n type transistor KT242A91 has been proposed. It is shown that established experimental characteristics for KT242A91 transistor correspond to similar transistor’s type characteristics.

A Novel Nitrogen Ion Implantation Technique for Turning Thin Film “Normally On” AlGaN/GaN Transistor into “Normally Off” Using TCAD Simulation

This study presents an innovative, low-cost, mass-manufacturable ion implantation technique for converting thin film normally on AlGaN/GaN devices into normally off ones. Through TCAD (Technology Computer-Aided Design) simulations, we converted a calibrated normally on transistor into a normally off AlGaN/GaN transistor grown on a silicon <111> substrate using a nitrogen ion implantation energy of 300 keV, which shifted the bandgap from below to above the Fermi level. In addition, the threshold voltage (Vth) was adjusted by altering the nitrogen ion implantation dose. The normally off AlGaN/GaN device exhibited a breakdown voltage of 127.4 V at room temperature because of impact ionization, which showed a positive temperature coefficient of 3 × 10−3 K−1. In this study, the normally off AlGaN/GaN device exhibited an average drain current gain of 45.3%, which was confirmed through an analysis of transfer characteristics by changing the gate-to-source ramping. Accordingly, the proposed technique enabled the successful simulation of a 100-µm-wide device that can generate a saturation drain current of 1.4 A/mm at a gate-to-source voltage of 4 V, with a mobility of 1487 cm2V−1s−1. The advantages of the proposed technique are summarized herein in terms of processing and performance.

A Transient Analysis for Amorphous Photoconductors

The study has been carried out for the transient response of photosensors fabricated by amorphous semiconductors under variable levels of excitation when switched off from steady-state. The curves for the entire range of the transient have been plotted in the terms of photoconductivity and they can be converted to current decay curves by multiplying with the applied electric field and the cross-sectional area of the sample. For this purpose, in the calculations, the transit time effect is included. Also, the switching time and gain of the photoconductor have been calculated. It is found that the current gain of the device increases as the density of thermal equilibrium electrons is made higher, compared to that of holes by moving the Fermi level upward. However, this also increased the switching time and its performance, as a switch becomes poorer.

Design and Evaluation of a High Current Gain Resonant Inverter for Subsea Electrical Heating

Direct electrical heating (DEH) is a well-established method for preventing hydrate formation inside subsea oil transfer pipelines. However, poor efficiency and high reactive power requirement of the existing line-frequency DEH systems have necessitated high-frequency power processing along with reactive power compensation. To meet these design objectives, a dc-ac converter using an LCCL resonant tank is presented in this paper to function as a high-frequency alternating current source. The LCCL resonant tank is tuned at the frequency of the peak tank current gain to maximize the heat generation and reduce the VA rating of the tank. The peak current gain operation also ensures zero voltage switching (ZVS) of the bridge inverter devices. Detailed frequency domain analysis and design guidelines are presented for the proposed LCCL resonant inverter (RI). Experimental results on a 10 A laboratory prototype and hardware-in-the-loop results for a 350 A system illustrate the advantages of the LCCL RI in DEH application.

Design and Evaluation of a High Current Gain Resonant Inverter for Subsea Electrical Heating

Direct electrical heating (DEH) is a well-established method for preventing hydrate formation inside subsea oil transfer pipelines. However, poor efficiency and high reactive power requirement of the existing line-frequency DEH systems have necessitated high-frequency power processing along with reactive power compensation. To meet these design objectives, a dc-ac converter using an LCCL resonant tank is presented in this paper to function as a high-frequency alternating current source. The LCCL resonant tank is tuned at the frequency of the peak tank current gain to maximize the heat generation and reduce the VA rating of the tank. The peak current gain operation also ensures zero voltage switching (ZVS) of the bridge inverter devices. Detailed frequency domain analysis and design guidelines are presented for the proposed LCCL resonant inverter (RI). Experimental results on a 10 A laboratory prototype and hardware-in-the-loop results for a 350 A system illustrate the advantages of the LCCL RI in DEH application.