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Feng Z.H.,Hebei Semiconductor Research Institute
2014 IEEE International Conference on Electron Devices and Solid-State Circuits, EDSSC 2014 | Year: 2014

Carbon electronics based on diamond and graphene field effect transistors have attracted significant attention for potential RF applications. Graphene is a 2 dimensional atomic layer of carbon atoms with unique electronic transport properties, such as outstanding carrier mobility and high carrier saturation velocity, which make graphene an excellent candidate for applications in high-speed analog electronics. Diamond also shows several physical properties that make it interesting for high power applications. In this paper, we discuss the current status and the prospects and problems of graphene and diamond transistors. Those properties of graphene and diamond relevant for transistors, including preparation of high-quality graphene film in large-scale, weak current saturation of the graphene transistors, growth of single crystalline and electronic diamond film, and doping of the diamond are reviewed. Our works on graphene and diamond electronics are also introduced. With the deep going of the investigation, carbon electronics should be used in the near future. © 2014 IEEE. Source


Fang Y.,University of Science and Technology Beijing | Fang Y.,Hebei Semiconductor Research Institute | Feng Z.,University of Science and Technology Beijing | Yin J.,University of Science and Technology Beijing | And 7 more authors.
IEEE Transactions on Electron Devices | Year: 2014

The design, fabrication, and characterization of AlGaN/GaN polarization-doped field-effect transistors (PolFETs) with graded heterostructure are presented in this paper. The 3-D profiles of carriers are obtained across the graded AlGaN/GaN heterostructure grown on a sapphire substrate, which brings about some novel features. The dc transfer and frequency characteristics exhibit bias-insensitive throughout the low-and high-voltage operating regions, demonstrating the potential for high linearity applications. In addition, dynamic I-V measurement was carried out to analyze the trapping behaviors. Negligible current collapses were observed in the unpassivated PolFETs with graded heterostructure, which can be explained in the aspect of unique energy band profiles of AlGaN/GaN graded heterostructures. © 2014 IEEE. Source


Zhao J.,Shandong University | Lin Z.,Shandong University | Luan C.,Shandong University | Zhou Y.,Shandong University | And 3 more authors.
Applied Physics Letters | Year: 2014

In this study, we investigated the electrical properties of the AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) with Ti/Al/Ni/Au gate electrodes using the measured capacitance-voltage, current-voltage characteristics, and micro-Raman spectroscopy. We found that the uneven distribution of the strain caused by the Schottky metals was a major factor that generates the polarization Coulomb field scattering in AlGaN/AlN/GaN HFETs, and after appropriate rapid thermal annealing (RTA) processes, the polarization Coulomb field scattering was greatly weakened and the two-dimensional electron gas electron mobility was improved. We also found that the Schottky barrier height and the DC characteristics of the devices became better after appropriate RTA. Of course, the electrical performances mentioned above became deteriorated after excessive annealing. © 2014 AIP Publishing LLC. Source


Zhao J.,Shandong University | Lin Z.,Shandong University | Luan C.,Shandong University | Chen Q.,Shandong University | And 4 more authors.
Superlattices and Microstructures | Year: 2015

Based on the forward current-voltage (I-V) characteristics and the capacitance-voltage ( C-V ) curves between the gate and source, a method to determine the strain of the AlGaN barrier layer under the gate in AlGaN/AlN/GaN heterostructure field-effect transistors (HFETs) has been presented. With this proposed method, the strain of the AlGaN barrier layer for the prepared AlGaN/AlN/GaN HFETs with the normal-Ohmic contacts and the side-Ohmic contacts has been analyzed and determined. It was found that the normal- Ohmic contact processing greatly affected the strain of the AlGaN barrier layer and the tensile strain of the AlGaN barrier layer was gradually reduced from the middle to the Ohmic contacts for the AlGaN/AlN/GaN HFETs with the normal-Ohmic contacts, while the strain of the AlGaN barrier layer was weakly affected by the side-Ohmic contact processing. © 2014 Elsevier Ltd. All rights reserved. Source


Feng Z.H.,Hebei Semiconductor Research Institute | Zhou R.,Hebei Semiconductor Research Institute | Xie S.Y.,University of Electronic Science and Technology of China | Yin J.Y.,Hebei Semiconductor Research Institute | And 5 more authors.
IEEE Electron Device Letters | Year: 2010

Enhancement-mode (E-mode) AlGaN/GaN heterojunction field effect transistors (HFETs) with a nominal gate length of 0.35 μm are fabricated on a SiC substrate by fluorine plasma ion implantation without the use of gate recess. The threshold voltage is measured to be +0.2 V by linear extrapolation from the transfer characteristics. The E-mode device exhibits a saturation drain current density of 735 mA/mm at a gate bias of 4 V, a peak transconductance of 269 mS/mm, a current-gain cutoff frequency fT of 39 GHz, and a maximum oscillation frequency fmax of 91 GHz. At 18 GHz, the fabricated E-mode device exhibits a maximum output power density of 3.65 W/mm, a linear gain of 11.6 dB, and a peak power-added efficiency of 42%. This is the first report of the large-signal performance of AlGaN/GaN E-mode HFETs in the Ku-band. © 2006 IEEE. Source

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