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Enhancement-mode AlGaN/GaN HEMTs fabricated by fluorine plasma treatment

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Journal of Semiconductors 2009年第12期30卷 21-24页

作者：全思郝跃马晓华谢元斌马骥刚 Key laboratory of Wide band Gap Semiconductor Materials and Devices Institute of MicroelectronicsXidian University

The fabrication of enhancement-mode AlGaN/GaN HEMTs by fluorine plasma treatment on sapphire substrates is reported. A new method is used to fabricate devices with different fluorine plasma RF power treatments on one wafer to avoid differences between different wafers. The plasma-treated gate regions of devices treated with different fluorine plasma RF powers were separately opened by a step-and-repeat system. The properties of these devices are compared and analyzed. The devices with 150 W fluorine plasma treatment power and with 0.6 μm gate-length exhibited a threshold voltage of 0.57 V, a maximum drain current of 501 mA/mm, a maximum transconductance of 210 mS/mm, a current gain cutoff frequency of 19.4 GHz and a maximum oscillation frequency of 26 GHz. An excessive fluorine plasma treatment power of 250 W results in a small maximum drain current, which can be attributed to the implantation of fluorine plasma in the channel.

关键词： high electron mobility transistors AlGaN/GaN fluorine plasma treatment threshold voltage

Evidence of GeO volatilization and its effect on the characteristics of HfO_2 grown on a Ge substrate

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Chinese Physics B 2013年第3期22卷 501-504页

作者：樊继斌刘红侠费晨曦马飞范晓娇郝跃 School of Microelectronics Key Laboratory of Wide Band-Gap Semiconductor Materials and DevicesXidian University

HfO2 films are deposited by atomic layer deposition（AlD） using tetrakis ethylmethylamino hafnium（TEMAH） as the hafnium precursor,while O3 or H2O is used as the oxygen *** annealing at 500℃ in nitrogen,the thickness of Ge oxide＇s interfacial layer decreases,and the presence of GeO is observed at the H2 O-based HfO2 interface due to GeO volatilization,while it is not observed for the O3-based *** difference is attributed to the residue hydroxyl groups or H2 O molecules in H2 O-based HfO2 hydrolyzing GeO2 and forming GeO,whereas GeO is only formed by the typical reaction mechanism between GeO2 and the Ge substrate for O3-based HfO2 after *** volatilization of GeO deteriorates the characteristics of the high-κ films after annealing,which has effects on the variation of valence band offset and the C-V characteristics of HfO2 /Ge after *** results are confirmed by X-ray photoelectron spectroscopy（XPS） and electrical measurements.

关键词： GeO volatilization H2 O-based HfO2 O3-based HfO2 thermal stability

Simulation research on offset field-plate used as edge termination in 4H-SiC merged PiN-Schottky diodes

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Chinese Physics B 2010年第4期19卷 394-397页

作者：陈丰平张玉明张义门吕红亮宋庆文 School of Microelectronics Key Laboratory of Wide Band-Gap Semiconductor Materials and DevicesXidian University

A new structure of 4H-silicon carbide （SIC） merged PiN-Schottky （MPS） diodes with offset field-plate （FP） as edge termination is developed. To understand the influences of 4H-SiC MPS diodes with offset FP on the characteristics, simulations have been done by using ISE TCAD. Related factors of offset FP have been studied as well to optimise the reverse characteristics of 4H SiC MPS diodes. The simulation results show that the device using offset FP can create a higher blocking voltage under reverse bias as compared with that using field guard rings. Besides, the offset FP does not cause any extra steps in the manufacture of MPS diodes.

关键词： 4H SiC merged PiN-Schottky offset field-plate reverse characteristics

Nonlinear characterization of GaN HEMT

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Journal of Semiconductors 2010年第11期31卷 18-23页

作者：陈炽郝跃杨凌全思马晓华张进城 National Key laboratory of Wide band-Gap Semiconductor Technology School of MicroelectronicsXidian University

DC I-V output,small signal and an extensive large signal characterization（load-pull measurements） of a GaN HEMT on a SiC substrate with different gate widths of 100μm and 1 mm have been carried *** the small signal data,it has been found that the cutoff frequencies increase with gate width varying from 100μm to 1 mm,owing to the reduced contribution of the parasitic *** devices investigated with different gate widths are enough to work in the C band and X *** large signal measurements include the load-pull measurements and power sweep measurements at the C band（5.5 GHz） and X band（8 GHz）.When biasing the gate voltage in class AB and selecting the source impedance,the optimum load impedances seen from the device for output power and PAE were localized in the load-pull *** results of a power sweep at an 8 GHz biased various drain voltage demonstrate that a GaN HEMT on a SiC substrate has good thermal conductivity and a high breakdown voltage,and the CW power density of 10.16 W/mm was *** the results of the power sweep measurement at 5.5 GHz with different gate widths, the actual scaling rules and heat effect on the large periphery device were analyzed,although the effects are not serious. The measurement results and analyses prove that a GaN HEMT on a SiC substrate is an ideal candidate for high-power amplifier design.

关键词： GaN HEMT load-pull measurements optimum load impedance power sweep measurement

Two-dimensional threshold voltage model of a nanoscale silicon-on-insulator tunneling field-effect transistor

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Chinese Physics B 2013年第3期22卷 528-533页

作者：李妤晨张鹤鸣张玉明胡辉勇王斌娄永乐周春宇 Key laboratory for Wide band-Gap Semiconductor Materials and Devices School of MicroelectronicsXidian University

The tunneling field-effect transistor（TFET） is a potential candidate for the post-CMOS *** this paper,a threshold voltage model is developed for this new kind of ***,two-dimensional（2D） models are used to describe the distributions of potential and electric field in the channel and two depletion *** based on the physical definition of threshold voltage for the nanoscale TFET,the threshold voltage model is *** accuracy of the proposed model is verified by comparing the calculated results with the 2D device simulation *** has been demonstrated that the effects of varying the device parameters can easily be investigated using the model presented in this *** threshold voltage model provides a valuable reference to TFET device design,simulation,and fabrication.

关键词： tunnel field-effect transistor band-to-band tunneling subthreshold swing gated P-I-N diode

Influence of double AlN buffer layers on the qualities of GaN films prepared by metal-organic chemical vapour deposition

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Chinese Physics B 2012年第12期21卷 403-407页

作者：林志宇张进成周昊李小刚孟凡娜张琳霞艾姗许晟瑞赵一郝跃 Key laboratory of Wide band-Gap Semiconductor Technology School of MicroelectronicsXidian University

In this paper we report that the GaN thin film is grown by metal-organic chemical vapour deposition on a sapphire （0001） substrate with double A1N buffer layers. The buffer layer consists of a low-temperature （lT） A1N layer and a high-temperature （HT） A1N layer that are grown at 600 ℃ and 1000 ℃, respectively. It is observed that the thickness of the lT-A1N layer drastically influences the quality of GaN thin film, and that the optimized 4.25-min-lT-A1N layer minimizes the dislocation density of GaN thin film. The reason for the improved properties is discussed in this paper.

关键词： GaN A1N buffer layer metal-organic chemical vapour deposition threading dislocations

Growth of InAlGaN Quaternary Alloys by Pulsed Metalorganic Chemical Vapor Deposition

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Chinese Physics letters 2016年第4期33卷 139-142页

作者：全汝岱张进成许晟瑞薛军帅赵一宁静林志宇任泽阳郝跃 Key laboratory of Wide band-Gap Semiconductor Technology School of MicroelectronicsXidian University

Epitaxial growth of InA1GaN/GaN structures are performed on the c-plane sapphire by pulsed metal organic chemical vapor deposition with different triethylgallium （TEGa） flows in the growth process of InA1GaN qua- ternary alloys. X-ray photoelectron spectroscopy results show that the A1/In ratio of the samples increases as the TEGa flows increase in the InAIGaN quaternary growth process. High-resolution x-ray diffraction results show that the crystal quality is improved with increasing TEGa flows. Morphology of the InA1GaN/GaN het- erostructures is characterized by an atomic force microscopy, and the growth mode of the InA1GaN quaternary shows a 21） island growth mode. The minimum surface roughness is 0.2Ohm with the TEGa flows equaling to 3.6 μool/rain in rms. Hall effect measurement results show that the highest electron mobilityμ is 1005.49 cm2/Vs and the maximal two-dimensional electron gas is 1.63 × 1013 em-2.

关键词： of Al by GaN in is AFM mode AIN

An X-band four-way combined GaN solid-state power amplifier

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Journal of Semiconductors 2010年第1期31卷 58-64页

作者：陈炽郝跃冯辉谷文萍李志明胡仕刚马腾 National Key laboratory of Wide band-Gap Semiconductor Technology School of MicroelectronicsXidian University

An X-band four-way combined GaN solid-state power amplifier module is fabricated based on a self- developed AlGaN/GaN HEMT with 2.5-mm gate width technology on SiC substrate. The module consists of an Al- GaN/GaN HEMT, Wilkinson power hybrids, a DC-bias circuit and microstrip matching circuits. For the stability of the amplifier module, special RC networks at the input and output, a resistor between the DC power supply and a transistor gate at the input and 3λ/4 Wilkinson power hybrids are used for the cancellation of low frequency self-oscillation and crosstalk of each amplifier. Under Vds = 27 V, Vgs = -4.0 V, CW operating conditions at 8 GHz, the amplifier module exhibits a line gain of 5 dB with a power added efficiency of 17.9%, and an output power of 42.93 dBm; the power gain compression is 2 dB. For a four-way combined solid-state amplifier, the power combining efficiency is 67.5%. It is concluded that the reduction in combining efficiency results from the non-identical GaN HMET, the loss of the hybrid coupler and the circuit fabricating errors of each one-way amplifier.

关键词： A1GaN/GaN HEMT solid-state power amplifiers Wilkinson hybrid coupler

Study of a double epi-layers SiC junction barrier Schottky rectifiers embedded P layer in the drift region

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Chinese Physics B 2010年第8期19卷 548-553页

作者：宋庆文张玉明张义门张倩吕红亮 School of Microelectronics Key Laboratory of Wide Band-Gap Semiconductor Materials and DevicesXidian University

This paper proposes a double epi-layers 4H-SiC junction barrier Schottky rectifier （JBSR） with embedded P layer （EPl） in the drift region. The structure is characterized by the P-type layer formed in the n-type drift layer by epitaxial overgrowth process. The electric field and potential distribution are changed due to the buried P-layer, resulting in a high breakdown voltage （BV） and low specific on-resistance （Ron,sp）. The influences of device parameters, such as the depth of the embedded P＋ regions, the space between them and the doping concentration of the drift region, etc., on BV and Ron,sp are investigated by simulations, which provides a particularly useful guideline for the optimal design of the device. The results indicate that BV is increased by 48.5% and Baliga＇s figure of merit （BFOM） is increased by 67.9% compared to a conventional 4H-SiC JBSR.

关键词： junction barrier Schottky rectifier 4H-SiC breakdown voltage specific on-resistance