The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
This paper describes efficient GaN/AlGaN HEMTs and MMICs for L/S-band (1-4 GHz) and X-band frequencies (8-12 GHz) on three-inch s.i. SiC substrates. Dual-stage MMICs in microstrip transmission-line technology yield a power-added efficiency of ??40% at 8.56 GHz for a power level of ??11 W. A single-stage MMIC yields a PAE of ??55% with 6 W of output power at VDS= 20 V. The related mobile communication...
This paper describes a balanced AlGaN/GaN HEMT single-stage power amplifier demonstrator for X-band frequencies in microstrip line technology on thinned s.i. SiC substrates. The design features a modular circuit concept and microstrip MMIC directional couplers with low impedance levels. These 3 dB-couplers designed for a center frequency of 10 GHz show a coupling factor of 3.5 dB plusmn 0.4 dB and...
AlGaN/GaN HEMT using field plate and recessed gate for X-band application was developed on SiC substrate. Internal matching circuits were designed to achieve high gain at 8 GHz for the developed device with single chip and four chips combining, respectively. The internally matched 5.52 mm single chip AlGaN/GaN HEMT exhibited 36.5 W CW output power with a power added efficiency (PAE) of 40.1% and power...
Two-dimensional transient analyses of AlGaN/GaN HEMTs and GaN MESFETs are performed in which a deep donor and a deep acceptor are considered in a semi-insulating buffer layer. Quasi-pulsed I-V curves are derived from the transient characteristics. It is studied how the existence of field plate affects buffer-related lag phenomena and current collapse. It is shown that in both FETs, the lag phenomena...
The design principles and technology of fabricating novel quantum-dot (QD) infrared (IR) detectors based on AlGaN/GaN high-electron-mobility transistors (HEMTs) with GaN QDs inserted into the AlGaN barrier of HEMT (QDIP-HEMT) are proposed. Computation of electron energy levels in GaN/AlGaN QWs' and QDs' is carried out and technology of its growth is developed.
This paper reports a novel approach in designing high frequency AlGaN/GaN HEMTs based on gate-drain field engineering utilizing a drain-connected field controlling electrode. The absence of frequency behavior degradation with drain bias as well as record high electron velocity values were obtained using gate-to-FCE separation of 0.5-0.7 mum. Thus, we demonstrated that the FCE is a powerful way to...
In this paper, we present high performance 0.25mum gate-length self-aligned AIGaN/GaN HEMTs on 6H-SiC substrates using a single ohmic step. Our recently developed Mo/Al/Mo/Au-based ohmic contact requiring annealing temperatures between annealing temperatures 500 and 600degC was utilized. Ohmic contact resistances between 0.3 - 0.5 ohm-mm have been achieved.
AIGaN/GaN high electron mobility transistors (HEMTs) are some of the most promising devices for power amplification. Important efforts have been taken to expand the operating frequency of these devices to mm-waves. As shown by Tasker et al., the drain parasitic resistance is one of the main factors limiting the current gain cut-off frequency (fT) and the power gain cut-off frequency (fmax) in high...
In this paper, we first demonstrate effects of thermal annealing on subthreshold slope in AlGaN/GaN HEMTs. Then, based on the temperature dependence of subthreshold slope, we introduce a new method to estimate interface trap density in these devices.The understanding of this interface trap is critical to optimize the gate modulation efficiency of these transistors and maximize their high frequency...
In this paper AlGaN/GaN high electron mobility transistor (HEMT) fabricated on diamond substrate is presented. Epitaxial AlGaN/GaN layers were first grown on high resistivity Si (111) substrate and transferred to polycrystalline diamond substrate, which was separately grown by chemical vapor deposition (CVD). It is concluded that these are the best-reported results for a transistor using GaN on diamond...
The paper reports small-signal and large-signal performance of 140 nm gatelength field-plated AlGaN/GaN HEMTs at Ka-band frequencies, in which the AlGaN/GaN HEMTs were fabricated with n+ GaN source ledge to reduce source access resistance such that the gate-to-drain feedback capacitance and breakdown voltage is not impacted.
In this work we report AIGaN/GaN HEMTs with nonalloyed ohmic contacts by large angle ion implantation with a contact resistance to the channel of 0.2 Omegamm.
In this work, we report on vertically scaled, 100nm gate-length Al 0.31Ga0.69N/AlN/GaN HEMTs with a low sheet resistance of 260Omega/square, an fT of 125 GHz and an f max (Ug) of 174 GHz. Careful device design and unique process features also resulted in a high peak Gm,ext of 498 mS/mm, an Idss of 1.2A/mm, and a gate-to-drain breakdown of 30V
In this report we present the switching measurements on large area AlGaN/GaN HEMT devices with high breakdown voltage achieved with the help of multiple field plates. AlGaN/GaN high electron mobility transistors have shown potential advantages over Si and SiC based transistors for high power switching. The very high electron mobility in the AlGaN/GaN HEMT system combined with the high density of polarization...
The paper reports on the characteristics of N-face AlGaN/GaN/AlGaN HEMTs. Ohmic contact optmization experiments based on the Ti/Al/Ni/Au metallization scheme commonly used for Ga-face AlGaN/GaN HEMTs were carried out and a low contact resistance of 1.3 Ohm/mm was achieved. The devices were then characterized before and after SiN passivation. Before passivation, large current dispersion was observed...
In this work, we use an ultra-thin InGaN layer below the GaN channel to increase the confinement of the electrons. In this novel approach, the polarization induced electric field in the InGaN layer is used to raise the conduction band energy in the buffer layer with respect to the channel. With this technique, a double-heterojunction transistor can be formed without the need of a high bandgap or p-doped...
A monolithic W-band preamplified diode detector based on 0.1- mu m pseudomorphic AlGaAs/InGaAs/GaAs HEMT (high electron mobility transistor) technology was developed. This chip consists of a Schottky diode detector with a two-stage W-band low-noise amplifier (LNA) and has a measured detector responsivity of 300 V/mW at 94 GHz and a tangential sensitivity of -62 dBm. This is the first reported monolithic...
Two-dimensionally-quantized electron transport in modulation-doped double-heterojunction structures is investigated using a Monte Carlo simulation. Enhanced low-field mobility in the quantum well is observed. This results from the reduction of optical phonon scattering rates, which can be attributed to the spread of the two-dimensional electron gas. It is demonstrated that the carrier transport related...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.