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Improved transport properties and mechanism in recessed-gate InAlN/GaN HEMTs using a self-limited surface restoration method

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Science China(Information Sciences) 2022年第10期65卷 285-292页

作者： Siyu LIU Xiaohua MA Jiejie ZHU Minhan MI Jingshu GUO Jielong LIU Yilin CHEN Qing ZHU Ling YANG Yue HAO Key Laboratory of Wide Bandgap Semiconductor Technology School of Microelectronics Xidian University School of Advanced Materials and Nanotechnology Xidian University

The etching process of high-performance recessed-gate In Al N/Ga N high-electron mobility transistors(HEMTs) has been actively researched. This paper proposes a post-etching self-limited surface restoration method that effectively suppresses the etching damage, enhancing the transport properties of recessed-gate In Al N/Ga N HEMTs. We fabricated planar-gate devices, inductively coupled plasma(ICP)-etched devices, and post-etching-treated(PET) devices. The damage caused by the ICP etching process severely deteriorated the transport properties of the devices. However, the post-etching process effectively inhibited the etching damage and improved the device transport properties. Through temperature-dependent tests and a simulation, the change in the peak transconductance was compared among different devices. The temperature-dependent optical phonon scattering and impurity-dependent remote charge scattering mechanisms were analyzed. The results confirmed that the etching damage significantly affected the channel electron scattering mechanism. The field-effect mobility showed a linear relationship with temperature, and the optical phonon scattering model illustrated that the field-effect mobility decreased with increasing temperature. The etching damage caused a decrease in the field-effect mobility from 1075.5 to 699.1 cm~2/V·s,which increased the fitting error between this empirical line and the optical phonon scattering fitting curve from 0.086 to 0.948, similar to the remote charge scattering fitting curve. The combined error range is from 0.896 to 0.054.

关键词： GaN InAlN/GaN HEMTs etching damage scattering mechanism

Structural, phonon, mechanical, optical, and thermodynamic properties of stable β-La_2S_3 from first-principles calculations

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Journal of Rare Earths 2017年第3期35卷 271-279页

作者：张显桂文华吴茜曾庆丰 School of Advanced Materials and Nanotechnology Xidian University International Center for materials Discovery School of Materials Science and EngineeringNorthwestern Polytechnical University

The band structures,density of states,phonon,optical properties,and thermodynamic properties of β-La_2S_3 were calculated from first-principles using the plane-wave pseudopotential method.First,the structures were fully relaxed through the first-principles method.Then,the zone-center phonon-mode frequencies were evaluated within the framework of density functional perturbation theory.Properties related to the structure,phonons,optics,elastic constants,and thermodynamics of β-La_2S_3 were reported.The dielectric function,refractive index,absorption coefficient,extinction coefficient,infrared（IR） reflectance,energy,heat capacity,and Debye temperature spectra were also given β-La_2S_3 was a direct-gap semiconductor,and calculation indicated that its energy gap was 0.191 eV.From the phonon spectra,it could be concluded that the lattice dynamics were stable.A strong IR reflection occurred in a range of 0-1000 nm,arising from several strong IR-active modes,resulting in poor transmission properties.Relatively good transmission properties were observed in the range above 2000 nm,with low reflectivity and dissipation due to the absence of IR-active or weak modes.

关键词： β-La2S3 first-principles optical properties elastic constant thermodynamic properties rare earths

Realtime observation of “spring fracture” like AlGaN/GaN HEMT failure under bias

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Science China(Information Sciences) 2024年第1期67卷 303-305页

作者： Qing ZHU Zhenni WANG Yuxiang WEI Ling YANG Xiaoli LU Jiejie ZHU Peng ZHONG Yimin LEI Xiaohua MA school of Microelectronics Xidian University State Key Discipline Laboratory of Wide Bandgap Semiconductor Technology Xidian University School of Advanced Materials and Nanotechnology Xidian University

The AlGaN/GaN HEMTs have been considered promising candidates for high-frequency and high-power applications,while the reliability issues greatly limit the commercialization of AlGaN/GaN HEMTs. In the past, the research on the reliability of devices was often based on Raman spectroscopy, cathodoluminescence, and TEM after failure of the devices, which is often considered to be the laborious and complicated “archaeological” kind of analysis [1].

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Single event upset rate modeling for ultra-deep submicron complementary metal-oxide-semiconductor devices

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Science China(Information Sciences) 2016年第4期59卷 56-66页

作者： Liang HE Hua CHEN Peng SUN Xiaofei JIA Chongguang DAI Jing LIU Long SHAO Zhaoqing LIU School of Advanced Materials and Nanotechnology Xidian University school of Electronic and Information Engineering Ankang University

Based on the integral method of single event upset(SEU) rate and an improved charge collection model for ultra-deep submicron complementary metal-oxide-semiconductor(CMOS) devices, three methods of SEU rate calculation are verified and compared. The results show that the integral method and the figure of merit(FOM) methods are basically consistent at the ultra-deep submicron level. By proving the validity of the carrier collection model considering charge sharing, the applicability of two FOM methods is verified, and the trends of single-bit and multiple-bit upset rates for ultra-deep submicron CMOS are analyzed.

关键词： ultra-deep submicron complementary metal-oxide-semiconductor devices single event upset rates charge sharing

Defect characterization of amorphous silicon thin film solar cell based on low frequency noise

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Science China(Information Sciences) 2018年第6期61卷 253-255页

作者： Linna HU Liang HE Hua CHEN Xiaofei JIA Ying HU Hongmei MA DANDan GUO Yu QIN School of Advanced Materials and Nanotechnology Xidian University school of Electronic and Information Engineering Ankang University

Dear editor,The reliability of solar cells is the key factor to determine the performance and lifetime of photovoltaic products.Compared to the insensitivity of traditional electrical detection and the limitations of ... 详细信息

关键词： Defect characterization of amorphous silicon thin film solar cell based on low frequency noise GR

Trimetallic synergistic optimization of 0D NiCoFe-P QDs anchoring on 2D porous carbon for efficient electrocatalysis and high-energy supercapacitor

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Journal of Energy Chemistry 2022年第11期31卷 149-158,I0006页

作者： Ruiqi Liu Xue-Rong Shi Yi Wen Xiaoxuan Shao Chen Su Jing Hu Shusheng Xu school of materials Engineering Shanghai University of Engineering ScienceShanghai 201620China School of Advanced Materials and Nanotechnology Xidian UniversityXi’an 710071ShaanxiChina school of materials Science and Engineering Suzhou University of Science and TechnologySuzhou 215009JiangsuChina

Developing multi-functional and low-cost noble-metal-free catalysts such as transition metal phosphides(TMPs)to replace noble-metal is of practical significance for energy conversion and storage.However,the low-durability and the agglomeration phenomenon during the electrochemical process limit their practical applications.Herein,using metal–organic frameworks(MOFs)as the precursor and a combined strategy of gradient temperature calcination and thermal phosphorization,a 0D/2D heterostructure of NiCoFe-P quantum dots(QDs)anchored on porous carbon was successfully developed as highly efficient electrode materials for overall water splitting and supercapacitors.Owing to this distinctive 0D/2D heterostructure and the synergistic effect of multi-metallic TMPs,the NiCoFe-P/C exhibits excellent electrocatalytic activity and durability of HER(87 mV at 10 mA cm^(-2))and OER(257 mV at 100 mA cm^(-2))in the KOH electrolyte.When NiCoFe-P/C is used as the two electrodes of electrolyzed water,only 1.55 V can drive the current density to 10 m A cm^(-2).At the same time,our NiCoFe-P/C possessed extraordinary property for charge storage.In particular,an ultra-high energy density of 100.8 Wh kg^(-1) was achieved at a power density of 900.0 W kg^(-1) for our assembled hybrid supercapacitor device NiCoFe-P/C(2:1)//activated carbon(AC).This work may open a potential way for the design of 0D/2D hybrid multifunctional nanomaterials based on TMPs QDs.

关键词： Metal-organic frameworks Transition metal phosphide quantum dots 0D/2D heterostructure Overall water splitting Supercapacitor First-principle calculations

First-principles study of electronic structure and optical properties of Er:Lu_(2)O_(3)

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Journal of Rare Earths 2021年第4期39卷 453-459页

作者： Xian Zhang Honglei Zhao Sen Gao Qingfeng Zeng School of Advanced Materials and Nanotechnology Xidian UniversityXi'an 710071China International Center for materials Discovery School of Materials Science and EngineeringNorthwestern Poly technical UniversityXi'an 710072China

In the present computational study,we found that Er:Lu_(2)O_(3)materials have promise for application in laser applications.The crystal structure and the electronic and optical properties of Er:Lu_(2)O_(3)materials were studied using first-principle calculations under the framework of density functional theory.Based on the experimental and calculated results,the structure of Lu_(2)O_(3)was established.The calculated results show that doping by Er^(3+)can effectively improve its absorption coefficient in the ultraviolet region and improve the static dielectric constant of Lu_(2)O_(3).As the doping concentration of Er^(3+)increases,the energy of the valence band electrons excited to the conduction band decreases,and the transition is more likely to occur.The absorption coefficient,reflectance,and electron energy loss spectroscopy are bathochromic shifted.The Lu_(2-x)Er_(x)O_(3)(0

关键词： Electronic structure First principles Optical property Er:Lu_(2)O_(3) Rare earths

Facile synthesis of high-entropy zirconate nanopowders and their sintering behaviors

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Journal of advanced Ceramics 2023年第3期12卷 498-509页

作者： Lin Tan Xinghua Su Jingxin Yang Pengchao Ji Fu Sun Qiang Tian Zhenhuan Zhao school of materials Science and Engineering Chang’an UniversityXi’an 710061China State Key Laboratory of Environment-Friendly Energy materials Southwest University of Science and TechnologyMianyang 621010China School of Advanced Materials and Nanotechnology Xidian UniversityXi’an 710126China

The challenge in synthesizing high-entropy ceramic(HEC)nanopowders is to suppress severe grain coarsening and particle agglomeration,which occur at elevated temperatures.This challenge could be addressed by the polyacrylamide gel method.In this work,single-phase high-entropy(Lao.2Ndo.2Smo.2Gdo.2 Ybo.2)2Zr2O7 and(Lao.2Ndo.2Yo.2Euo.2Gdo.2)2Zr2O7 nanopowders without agglomeration were successfully synthesized using the polyacrylamide gel method for the first time.The results showed that phase composition,particle size,and agglomeration degree of the nanopowders were greatly influenced by the molar ratio of acrylamide(AM)/Zr and calcination temperature.These as-synthesized high-entropy zirconate(HEZ)nanopowders could be sintered into fully dense ceramics at 1500 C for 2 h.These HEZ nanopowders showed a phase transformation from a defect-fluorite phase to a pyrochlore phase with the increase of sintering temperature.Additionally,two-step sintering of these nanopowders was conducted,and the HEZ ceramics with fine grains were prepared.The polyacrylamide gel method is simple and easily operated,which is a facile approach of producing the HEC nanopowders with excellent sinterability.

关键词： high-entropy ceramics(HECs) nanopowders zirconate acrylamide(AM) sintering

Improvement of the off-state breakdown voltage with field plate and low-density drain in AlGaN/GaN high-electron mobility transistors

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Chinese Physics B 2015年第3期24卷 332-335页

作者：张鹏赵胜雷侯斌王冲郑雪峰马晓华张进成郝跃 Key Laboratory of Wide Band-Gap Semiconductor materials and Devices School of Advanced Materials and NanotechnologyXidian University

We present an AlGaN/GaN high-electron mobility transistor（HEMT） device with both field plate（FP） and lowdensity drain（LDD）. The LDD is realized by the injection of negatively charged fluorine（F-） ions under low power in the space between the gate and the drain electrodes. With a small-size FP and a LDD length equal to only 31% of the gate-drain spacing, the device effectively modifies the electric field distribution and achieves a breakdown voltage enhancement up to two times when compared with a device with only FP.

关键词： GaN,high-electron mobility transistors,fluorine,electric field