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AlGaN/GaN Heterojunction Field Effect Transistor (HFET) embedded GaN piezotransistive microcantilevers are used as potentiometric sensors. 10mV potential difference between the cantilever tip and a metal electrode is successfully measured at the cantilever resonance frequency. Moreover, quality factor enhancement of the cantilever at low pressure is demonstrated.
The purpose of this work is to investigate the effect of ohmic electrode processing on the breakdown voltage of AlGaN/GaN HEMTs. The impact of ultrasonic cleaning condition during the lift-off process on metal edge definition was investigated. It was verified that the shape of the ohmic electrode was indeed crucial for ensuring high breakdown voltage characteristics.
This paper describes breakdown characteristics of AlGaN/GaN high electron mobility transistors (HEMTs) with multi-finger gate patterns. We studied the spatial profile of electroluminescence (EL) from AlGaN/GaN HEMTs under high drain and near pinch-off gate bias. As a result, different EL emission profiles and breakdown characteristics were observed depending on the drain electrode pattern of the devices.
In this work, we investigated the effect of shape irregularities of drain electrode on the breakdown voltage of AlGaN/GaN HEMTs. We found that some random devices having rough metal edge definition tend to have lower breakdown voltages. In addition, these devices showed localized high intensity luminescence observed under near pinch-off condition. This is likely due to electric field concentration...
In several decades, the world has witnessed various dramatic changes since applying of semiconductor. The performance requirements of semiconductor products are continue increasing while the technology is improving. In order to satisfy the requirements, the researches of new material and device structure is necessary. This paper shows a new structure of GaN HEMT. An AlGaN/GaN HEMT consists of AlGaN/GaN...
This paper describes the effect of thickening Au-plated ohmic electrodes in AlGaN/GaN HEMTs on the drain current and on-resistance. By increasing the thickness of Au-plated ohmic electrodes up to 5 µm, the fabricated AlGaN/GaN HEMT with a total gate width from 2 to 10 mm exhibited an increase in the maximum drain current by about 50 % and a reduction in the on-resistance by more than 40 %.
This paper describes fabrication and characterization of AlGaN/GaN HEMTs for large current operation. By depositing a 1000nm-thick Au metal on Ti/Al/Mo/Au source and drain ohmic contacts, a drain current of more than 4 amperes has been achieved with a total gate width of 10 mm. We discuss the dependence of saturation drain current on gate width in terms of Au thickness and source/drain ohmic electrode...
GaN Super Heterojunction Field Effect Transistors (Super HFETs) based on the polarization junction (PJ) concept are demonstrated on Sapphire substrates. These Super HFETs were fabricated from a GaN/Al0.23Ga0.77N/GaN hetero structure with 2D hole and electron gas densities of 1.1×1013 and 9.7×1012 cm−2 at the respective hetero-interfaces. The Super HFETs show breakdown voltage above 700 V with on-resistances...
Two-dimensional transient analysis of gate-field-plate AlGaN/GaN HEMTs with a backside electrode is performed by considering a deep donor and a deep acceptor in a buffer layer. It is shown that the introduction of gate field plate is effective in reducing buffer-related lag and current collapse when the acceptor density in the buffer layer is high. On the other hand, the introduction of backside electrode...
It has been proposed in the literature to use metal field plates (FPs) in order to increase the breakdown voltage (BV) of AlGaN/GaN HEMTs. In this article we analyze the possibility of using multiple FPs to increase the gate-to-drain BV. We show that FPs with variable oxide thickness (with thinner oxide towards the gate electrode and thicker oxide thickness towards the drain electrode) increase the...
Recently we have developed a numerical technique for the optimization of parameters in semiconductor devices. This technique allows the computation ("redesign") of the doping profiles of most semiconductor devices such as MOSFETs and SOI transistors, in order to decrease (or increase) the values of given parameters of the device. In this presentation we show how to adjust this optimization...
The purpose of this work was to develop a TCAD device model to study the electrical and thermal characteristics of the AlGaN/GaN HEMT in the time domain in contrast to a DC thermal equilibrium analysis. We first examined a channel temperature technique that utilizes temperature dependence of gate voltage on gate current to predict channel temperature. The predicted channel temperature of Method 3104...
We have designed a high breakdown yielding AlGaN/GaN HEMTs on 4 inch silicon wafer without using a field plate or increasing the gate-drain length (Lgd). Our approach is based on improving the total thickness (Tgd) of the AlGaN/GaN epi-layers as high as 9 μm which improves the quality of i-GaN. Growing i-GaN on thick buffer reduces the dislocation density, increases the resistance between the surface...
Novel design concepts and cutting edge results are presented for high-power AlGaN/GaN Heterostructure Field-Effect Transistor switches for power converters, control and radio-frequency applications. For power switching, the HFET design has to be different from that of power amplifiers in order to minimize the contact resistance and avoid current crowding in the metal electrodes of large-periphery...
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