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Current dispersion is an issue in AlGaN/GaN HEMTs. Different methods have been reported to investigate this phenomenon. This study reports an investigation of intrinsic components from small-signal model of AlGaN/GaN HEMTs right after off-state bias in linear and saturation regions in addition to drain-lag measurement. Different variations on the intrinsic components after off-state bias in linear...
Admittance spectroscopy of pristine AlGaN/GaN metal-semiconductor interface reveals the distributed trap activation energy in the order of 0.24 eV by mercury probe capacitance-voltage (C-V) measurements. The trap densities of states (Dit) of these traps were extracted in the range of ∼1.9×1012 eV−1cm−2 with the reverse bias voltage ranging from −5 Volts to 0 Volt. A very good fitting of admittance...
In this work, we report GaN high-electron-mobility-transistors (HEMTs) on SiC with field plates of various dimensions for optimum performance. 0.6 μm gate length, 3 μm drain source space AlGaN/GaN HEMTs with field-plate lengths of 0.2, 0.3, 0.5 and 0.7 μm have been fabricated. Great enhancement in radio frequency (RF) output power density was achieved with acceptable compromise in small signal gain...
AlGaN/GaN High Electron Mobility Transistors (HEMTs) are well recognized today as the best electron devices for power amplification in microwave frequency range for power transmitters and RADARs. GaN-based devices promise to have the best power performance not only in signal amplification area but also in huge area of power conversion. This paper describes what unique properties of GaN enable handling...
The accuracy of different thermography techniques for the determination of AlGaN/GaN HEMT channel temperature was investigated. Micro-Raman thermography, a novel electrical testing method, and IR thermography were applied to measure the temperature in the active region of AlGaN/GaN HEMTs with different device geometries. Due to its accepted accuracy, micro-Raman thermography was performed on different...
The cathodoluminescent spectroscopy (CLS) in order to examine AlGaN/GaN modulation-doped field-effect transistors that display degraded source-drain current characteristics after 1.8-MeV proton irradiation, along with bulk heterojunctions of materials of field-effect transistor. For both cases, we have observed distinct changes in the spectral emission features due to decreased internal electric-field...
The ability to accurately determine the breakdown voltage of microwave transistors is critical to the design of high power microwave amplifiers. The optimal bias point and output impedance should be selected to ensure that the load line of the device during peak output power does not intersect the portion of the IV curve where the device breaks down. This paper presents a technique to determine a...
In this paper, we present the temperature dependent microwave noise measurements and modeling of AlGaN/GaN HEMTs on Si substrate over a wide temperature range from -50 to 200degC. The typical noise parameters including minimum noise figure (NFmin), noise equivalent resistance (Rn), optimum source reflection coefficient (Gammaopt) and associate gain (Ga) at different temperatures were measured and...
DC-Step-Stress-Tests of GaN HEMTs have been performed on wafers with and without GaN-cap. The tests consist of a step ramping of drain-source voltage VDS by 5 V every two hours at off-state. The irreversible evolution of leakage current starting at a certain drain voltage has been taken as a criterion for the onset of device degradation. It has been stated that there is a stability limit for VDS depending...
High-performance internally-matched GaN HEMT with 0.3 mum gate length and 4times2.5 mm of the total gate width was successfully fabricated. The large signal RF characteristics of the internally-matched device were measured at 8 GHz. A maximum output power of 64.5 W, a gain of 7.2 dB and a peak power-added efficiency (PAE) of 40% was obtained, respectively.
AlGaN/GaN heterostructure field effect transistors with different gate recess depths have been fabricated using an ICP etch process. Subsequently, electrical DC characterization has been performed. The results have been compared with the theoretical predictions according to the simple charge control model, showing that for a given AlGaN/GaN structure there is an optimum thickness with respect to the...
The paper reports microwave properties of AlGaN/GaN HEMT fabricated on sapphire substrate. The measured transition frequency as well as maximum frequency of oscillation was taken as a figure of merit for comparison of influence of different treatment. Using 2 mum length of gate electrode 7.425 GHz transition frequency as well as 23.437 GHz maximum frequency of oscillation was achieved. Significant...
Low frequency noise (LFN) is a reliable diagnostic tool to evaluate and locate the defects of a technology. In this study, LFN is used to assess effects of deuterium (H+ ions) in diffusion condition on the robustness of 0.25 *2*75 mum2 gate area AlGaN/GaN high electron mobility transistors (HEMT) grown on Si substrate. H+ ions are diffused from the above AlGaN/GaN layer through the AlGaN/GaN interface...
We report on the development of a integrated Raman - IR thermography technique to probe self-heating in active devices. We compare and discuss advantages of both techniques in terms of spatial resolution on the example of AlGaN/GaN HFET devices. While traditional infra-red (IR) thermography can provide fast overviews of self-heating in the devices over large scales, its use for extraction of channel...
AlGaN/GaN high-electron-mobility transistors (HEMTs) which have the Schottky contact only formed on the unetched region and the SiO2 passivation using an inductively coupled chemical vapor deposition (ICP-CVD) was proposed. The proposed device does not have any Schottky contact on the dry-etched region because the Schottky contact formation is performed prior to the mesa isolation, which suppresses...
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