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Chinese Physics B 2015年第8期24卷 534-538页

作者：吕元杰冯志红顾国栋尹甲运房玉龙王元刚谭鑫周幸叶林兆军冀子武蔡树军 National Key Laboratory of Application Specific Integrated Circuit (ASIC) Hebei Semiconductor Research Institute School of Physics Shandong University

In this study rectangular AlGaN/AlN/GaN heterostructure field-effect transistors(HFETs) with 22-nm and 12-nm AlGaN barrier layers are fabricated, respectively. Using the measured capacitance–voltage and current–voltage characteristics of the prepared devices with different Schottky areas, it is found that after processing the device, the polarization coulomb field(PCF) scattering is induced and has an important influence on the two-dimensional electron gas electron ***, the influence of PCF scattering on the electron mobility is enhanced by reducing the AlGaN barrier *** leads to the quite different variation of the electron mobility with gate bias when compared with the AlGaN barrier thickness. This mainly happens because the thinner AlGaN barrier layer suffers from a much stronger electrical field when applying a gate bias, which gives rise to a stronger converse piezoelectric effect.

关键词： AlGaN/AlN/GaN barrier layer thickness electron mobility polarization coulomb field scattering

Influence of temperature on strain-induced polarization coulomb field scattering in AlN/GaN heterostructure field-effect transistors

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Chinese Physics B 2014年第7期23卷 645-648页

作者：吕元杰冯志红林兆军郭红雨顾国栋尹甲运王元刚徐鹏宋旭波蔡树军 National Key Laboratory of Application Specific Integrated Circuit (ASIC) Hebei Semiconductor Research Institute School of Physics Shandong University

Electron mobility scattering mechanism in AlN/GaN heterostuctures is investigated by temperature-dependent Hall measurement, and it is found that longitudinal optical phonon scattering dominates electron mobility near room temperature while the interface roughness scattering becomes the dominant carrier scattering mechanism at low temperatures （~ 100 K）. Based on measured current-voltage characteristics of prepared rectangular AlN/GaN heterostructure field-effect transistor under different temperatures, the temperature-dependent variation of electron mobility under different gate biases is inves- tigated. The polarization coulomb field （PCF） scattering is found to become an important carrier scattering mechanism after device processing under different temperatures. Moreover, it is found that the PCF scattering is not generated from the thermal stresses, but from the piezoelectric contribution induced by the electrical field in the thin A1N barrier layer. This is attributed to the large lattice mismatch between the extreme thinner AlN barrier layer and GaN, giving rise to a stronger converse piezoelectric effect.

关键词： AlN/GaN electron mobility polarization coulomb field scattering polarization

The influence of the channel electric field distribution on the polarization coulomb field scattering in AlN/GaN heterostructure field-effect transistors

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Journal of Semiconductors 2014年第12期35卷 48-52页

作者：于英霞林兆军吕元杰冯志红栾崇彪杨铭王玉堂 School of Physics Shandong University Scienceand Technologyon ASIC Laboratory Hebei Semiconductor Research Institute

Based on the measured capacitance–voltage（C–V） curves and current–voltage（I–V） curves for the prepared differently-sized AlN/GaN heterostructure field-effect transistors（HFETs）, the I–V characteristics of the AlN/GaN HFETs were simulated using the quasi-two-dimensional（quasi-2D） model. By analyzing the variation in the electron mobility for the two-dimensional electron gas（2DEG） with the channel electric field, it is found that the different polarization charge distribution generated by the different channel electric field distribution can result in different polarization coulomb field（PCF） scattering. The 2DEG electron mobility difference is mostly caused by the PCF scattering which can reach up to 899.6 cm^2/（V·s）（sample a）, 1307.4 cm^2/（V·s）（sample b）,1561.7 cm^2/（V s）（sample c） and 678.1 cm^2/（V·s）（sample d）, respectively. When the 2DEG sheet density is modulated by the drain–source bias, the electron mobility for samples a, b and c appear to peak with the variation of the 2DEG sheet density, but for sample d, no peak appears and the electron mobility rises with the increase in the2 DEG sheet density.

关键词： AlN/GaN heterostructure field-effect transistors channel electric field distribution polarization coulomb field scattering electron mobility

Influence of Schottky drain contacts on the strained AlGaN barrier layer of AlGaN/AlN/GaN heterostructure field-effect transistors

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Chinese Physics B 2013年第4期22卷 394-398页

作者：曹芝芳林兆军吕元杰栾崇彪王占国 School of Physics Shandong University Laboratory of Semiconductor Materials Science Institute of Semiconductors Chinese Academy of Sciences

Rectangular Schottky drain AlGaN/AlN/GaN heterostructure field-effect transistors （HFETs） with different gate contact areas and conventional AlGaN/AlN/GaN HFETs as control were both fabricated with same size. It was found there is a significant difference between Schottky drain AlGaN/AlN/GaN HFETs and the control group both in drain series resistance and in two-dimensional electron gas （2DEG） electron mobility in the gate–drain channel. We attribute this to the different influence of Ohmic drain contacts and Schottky drain contacts on the strained AlGaN barrier layer. For conventional AlGaN/AlN/GaN HFETs, annealing drain Ohmic contacts gives rise to a strain variation in the AlGaN barrier layer between the gate contacts and the drain contacts, and results in strong polarization coulomb field scattering in this region. In Schottky drain AlGaN/AlN/GaN HFETs, the strain in the AlGaN barrier layer is distributed more regularly.

关键词： AlGaN/AlN/GaN HFET Schottky drain contact AlGaN barrier layer strain polarization coulomb field scattering

Comparison for the carrier mobility between the III–V nitrides and AlGaAs/GaAs heterostructure field-effect transistors

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Journal of Semiconductors 2014年第9期35卷 65-70页

作者：栾崇彪林兆军吕元杰冯志红赵景涛周阳杨铭 School of Physics Shandong University National Key Laboratory of Application Specific Integrated Circuit(ASIC) Hebei Semiconductor Research Institute

Using the measured capacitance-voltage curves ofNi/Au Schottky contacts with different areas and the current-voltage characteristics for the A1GaAs/GaAs, A1GaN/A1N/GaN and ***/A1N/GaN heterostructure field-effect transistors （HFETs） at low drain-source voltage, the two-dimensional electron gas （2DEG） electron mobility for the prepared HFETs was calculated and analyzed. It was found that there is an obvious difference for the variation trend of the mobility curves between the Ⅲ-V nitride HFETs and the A1GaAs/GaAs HFETs. In the III-V nitride HFETs, the variation trend for the curves of the 2DEG electron mobility with the gate bias is closely related to the ratio of the gate length to the drainto-source distance. While the ratio of the gate length to the drainto-source distance has no effect on the variation trend for the curves of the 2DEG electron mobility with the gate bias in the A1GaAs/GaAs HFETs. The reason is attributed to the polarization coulomb field scattering in the Ⅲ-V nitride HFETs.

关键词： Ⅲ-V nitride and AlGaAs/GaAs HFETs polarization coulomb field scattering 2DEG electron mo-bility