In this paper, a frequency domain, nonlinear, behavioral model for RF power transistors, based on an artificial neural network (ANN), is proposed and validated. The model is identified using the back-propagation algor...
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In this paper, a frequency domain, nonlinear, behavioral model for RF power transistors, based on an artificial neural network (ANN), is proposed and validated. The model is identified using the back-propagation algorithm from the incident and scattered wave data of the RF transistor. The model has been extracted and validated on Cree GaN HEMT device. Both simulation and measurement examples are presented. Compared with existing nonlinear transistor behavioral models, which are all input-power dependent, the new model is able to effectively predict the behavior of a transistor over the entire Smith chart, at different levels of input power with only a single set of model coefficients.
We fabricated the depletion-mode high-electron mobility transistors (HEMTs) based on a quaternary barrier InAlGaN/AlN/GaN heterostructure on SiC substrate. A 60-nm rectangular-shape gate was defined through e-beam lit...
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Silicon-based MEMS microthruster matrix has gained great attention as a micro-impulsion system in recent years, especially in application of attitude control of the nanosatellites. Although silicon serves well as the ...
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Silicon-based MEMS microthruster matrix has gained great attention as a micro-impulsion system in recent years, especially in application of attitude control of the nanosatellites. Although silicon serves well as the structural material for microthruster matrix in several aspects, its ability to resist ablation is rather weak. In this paper, SiC membrane is introduced to the surface of micro-chambers in order to enhance the ablation resistance of silicon-based MEMS microthrusters. A time-efficient four-step deposition process was carried out to prepare high-quality cavity-free SiC membrane. Microthrusters with SiC membrane coverage were tested under high-energy propellant experiment. The result shows that the SiC membrane can perfectly resist the ablation of microthrusters from nano-Al/CuO propellant.
CaN films with an AlxGa1-xN/AlyGa1-xN superlattice （SL） buffer layer are grown on Si（111） substrates by metal-organic chemical vapor deposition （MOCVD）. The structure and strain properties of the samples are stu...
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CaN films with an AlxGa1-xN/AlyGa1-xN superlattice （SL） buffer layer are grown on Si（111） substrates by metal-organic chemical vapor deposition （MOCVD）. The structure and strain properties of the samples are studied by optical microscopy, Raman spectroscopy, x-ray diffractometry and atomic force microscopy. The results show that the strain status and crystalline quality of the CaN layers are strongly dependent on the difference of the Al composition between AlxCa1-xN barriers and AlyCa1-yN wells in the SLs. With a large Al composition difference, the CaN film tends to generate cracks on the surface due to the severe relaxation of the SLs. Otherwise, when using a small Al composition difference, the crystalline quality of the CaN layer degrades due to the poor function of the SLs in filtering dislocations. Under an optimized condition that the Al composition difference equals 0.1, the crack-free and compressive strained CaN film with an improved crystalline quality is achieved. Therefore, the AlxGa1-xN/AlyGal-yN SL buffer layer is a promising buffer structure for growing thick CaN films on Si substrates without crack generation.
In this paper, crack-free GaN films with step-graded AlGaN transition layer and AlGaN superlattice layer as buffer layers were grown on Si(111) substrate by metal-organic chemical vapor deposition(MOCVD). The combinat...
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The ground-state energy level （GEL） and electron distribution of GaAs pseudomorphic high-electron-mobility transistors （PHEMTs） are analyzed by a self-consistent solution to the Schrodinger-Poisson equations. The ...
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The ground-state energy level （GEL） and electron distribution of GaAs pseudomorphic high-electron-mobility transistors （PHEMTs） are analyzed by a self-consistent solution to the Schrodinger-Poisson equations. The indium composition and thickness of the InGaAs channel are optimized according to the GEL position. The GEL position is not in direct proportion to 1/d^2 （d is the channel thickness） by considering the influence of electron distribution in the InGaAs channel. Indium composition 0.22 and channel thickness 9 nm are obtained by considering the mismatch between InGaAs and AlGaAs. Several PHEMT samples are grown according to the theoretical results and mobility 6300 cm^2 /V.s is achieved.
The paper reports high performance enhancement-mode MOS-HEMT based on quaternary InAlGaN barrier. A self-aligned gate technology is used for gate recessing, dielectric deposition and gate electrode formation processes...
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ISBN:
(纸本)9781509046140
The paper reports high performance enhancement-mode MOS-HEMT based on quaternary InAlGaN barrier. A self-aligned gate technology is used for gate recessing, dielectric deposition and gate electrode formation processes, where improved digital recessing process as well as O2 plasma-assisted Al 2 O 3 gate dielectric is developed. Fabricated E-mode MOS-HEMT delivers a record output current density of 1.7A/mm with a threshold voltage (V TH ) of 1.5 V, and a small on-resistance (R on ) of 2.0 Q-mm. Excellent V TH hysteresis and greatly improved gate leakage characteristics are also demonstrated.
A high-performance enhancement-mode （E-mode） gallium nitride （GaN）-based metal-insulator- semiconductor high electron mobility transistor （MIS-HEMT） that employs a 5-nm-thick aluminum gallium nitride （Al0.3Ga0...
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A high-performance enhancement-mode （E-mode） gallium nitride （GaN）-based metal-insulator- semiconductor high electron mobility transistor （MIS-HEMT） that employs a 5-nm-thick aluminum gallium nitride （Al0.3Ga0.7N） as a barrier layer and relies on silicon nitride （SIN） passivation to control the 2DEG density is presented. Unlike the SiN passivation, aluminum oxide （AL2O3） by atomic layer deposition （ALD） on A1GaN surface would not increase the 2DEG density in the heterointerface. ALD AL2O3 was used as gate insulator after the depletion by etching of the SiN in the gate region. The E-mode MIS-HEMT with gate length （LG） of 1 μm showed a maximum drain current density （IDs） of 657 mA/mm, a maximum extrinsic transconductance （gin） of 187 mS/ram and a threshold voltage （Vth） of 1 V. Comparing with the corresponding E-mode HEMT, the device performances had been greatly improved due to the insertion of AL2O3 gate insulator. This provided an excellent way to realize E-mode A1GaN/GaN MIS-HEMTs with both high Vth and IDS.
High power performance AlGaN/GaN HEMT devices with 0.1 μm Y-shaped gates encapsulated with low-κ BCB are reported. The maximum drain current and transconductance of the device are 1.15 A/mm and 350 mS/mm, respective...
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ISBN:
(纸本)9781509018314
High power performance AlGaN/GaN HEMT devices with 0.1 μm Y-shaped gates encapsulated with low-κ BCB are reported. The maximum drain current and transconductance of the device are 1.15 A/mm and 350 mS/mm, respectively. The two-terminal breakdown voltage exceeds 30 V, which ensures a high operating voltage. Using the novel 0.1 μm low parasitic Y-shaped gate associated with AlGaN back barrier, a f T of 90 GHz and a f max of 170 GHz were obtained for the device. Through measurements of the W-band GaN MMIC PA, ability of 1.55 W/mm output power density was achieved for the device at frequency of 92 GHz. These outstanding performance indicates the devices are suitable for W-band MMIC applications.
Two broadband detectors at W-band and D-band are analyzed and designed with low barrier Schottky diodes. The input circuit of the detectors is realized by low and high impedance microstrip lines, and their output circ...
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Two broadband detectors at W-band and D-band are analyzed and designed with low barrier Schottky diodes. The input circuit of the detectors is realized by low and high impedance microstrip lines, and their output circuit is composed of a radio frequency （RF） bandstop filter and a tuning line for optimum reflection phase of the RF signal. S-parameters of the complete circuit are exported to a circuit simulator for voltage sensitivity analysis. For the W band detectors, the highest measured voltage sensitivity is 11800 mV/mW at 100 GHz, and the sensitivity is higher than 2000 mV/mW in 80-104 GHz. Measured tangential sensitivity （TSS） is higher than -38 dBm, and its linearity is superior than 0.99992 at 95 GHz. For the D band detector, the highest measured voltage sensitivity is 1600 mV/mW, and the typical sensitivity is 600 mV/mW in 110-170 GHz. TSS is higher than -29 dBm, and its linearity is superior than 0.99961 at 150 GHz.
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