The breakdown and the current collapse characteristics of high electron mobility transistors (HEMTs) with a low power F-plasma treatment process are investigated. With the increase of F-plasma treatment time, the saturation current decreases, and the threshold voltage shifts to the positive slightly. Through analysis of the Schottky characteristics of the devices with different F-plasma treatment times, it was found that an optimal F-plasma treatment time of 120 s obviously reduced the gate reverse leakage current and improved the breakdown voltage of the devices, but longer F-plasma treatment time than 120 s did not reduce gate reverse leakage current due to plasma damage. The current collapse characteristics of the HEMTs with F-plasma treatment were evaluated by dual pulse measurement at different bias voltages and no obvious deterioration of current collapse were found after low power F-plasma treatment.

Chong Wang;Chong Chen;Yunlong He;Xuefeng Zheng;Xiaohua Ma;进成 张;Wei Mao;跃 郝

Journal of Semiconductors

2014-1

This paper presents an optimized architecture of shared memory controller in packet processing multi-processor system on chip (MPSoC). The rotation priority algorithm in arbitration mechanism is ameliorated so that fairness of the memory access response and continuity of read/write commands are guaranteed. A 'ping-pong' structure is adopted in SRAM interface logic which optimizes the memory data throughput. The test results show that the proposed architecture improves total performance by up to 64.1% compared with original memory controller and the 100% peak utilization of the data bus can be obtained. The efficiency of memory access shared by multi-processor cores is advanced remarkably.

江义 史;Ai Nv An;Kang Li;跃 郝;Pei Yan Liu;Ying Kang

2010

With increasing scale of Network-on-Chips (NoCs), the power caused by long line wires between cores counts for a significant proportion of the NoCs energy consumption. Most of the study on NoCs topologies assume that interconnect wires between cores are same length and are short lines. Taking 2D 4x4 torus network as an example in this paper, we present a long line interconnects network model for analyzing latency and energy consumption of NoCs. Simulation shows the different between this model and short line model. We also propose a novel approach based on low swing circuit using MOS current mode logic (MCML) to decreasing power consumption of long line wires in NoCs. Compared to the conventional full swing circuit, Simulation results show that the total NoCs link energy consumption can be reduced.

Yao Lei;Cai Jueping;Li Zan;跃 郝;Huang Gang;Wang Shaoli

2010

In this paper, large-area uniform multilayer graphene films were synthesized on copper in one growth route by modified low pressure chemical vapor deposition (LPCVD) method by introducing an assembly into the conventional LPCVD method. Scanning electronic microscopy, optical microscopy, Raman spectroscopy, ellipsometry, and transmission electron microscopy were used to characterize the graphene films. The results showed that the graphene films were multilayer. And there are about six layers with good continuity and uniformity. Meanwhile, the growth mechanism was illustrated by a growth model based on the analysis of the effects of the introduced assembly on the generation of the activated carbon atoms and on the catalysis of Cu molecules.

Yonggui Shi;Dong Wang;进成 张;Peng Zhang;Xuefang Shi;跃 郝

Materials and Manufacturing Processes

2015-6-3

A high-linearity and high-gain AlGaN/GaN HEMTs with a 100-nm gate were demonstrated. The device employs transitional recessed gate (TRG) along the gate width for millimeter wave power application. The gradually changing gate recess depth was created using transitional dosed photoetching. Accurate etching ensured that the FET-elements have a continued \text{V}-{\mathrm {ts}} offset in the local equivalent threshold voltage ( \text{V}-{\mathrm {th}} ) in different areas. The device exhibits a high \text{I}-{\mathrm {d,max}} of 1.12 A/mm and a high peak extrinsic \text{g}-{\mathrm {m}} of 374 mS/mm with an improved gate swing >2.6 V, much higher than that of Fin-HEMT. Excellent RF performance was shown, including \text{f}-{\mathrm {T}}/\text{f}-{\mathrm {max}} =61.8 /148.8 GHz, \text{G}-{\mathrm {as}}/\text{G}-{\mathrm {linear}} = {9.98} / 12dB at 30 GHz. To the best of our knowledge, this is the best associated gain and linearity performance reported to date for AlGaN/GaN HEMTs. This letter has great potential for high gain and linearity millimeter wave power applications, which are needed for future communication systems.

Sheng Wu;Xiaohua Ma;Ling Yang;Minhan Mi;Meng Zhang;Mei Wu;Yang Lu;Hengshuang Zhang;Chupeng Yi;跃 郝

IEEE Electron Device Letters

2019-6

We investigate the dispersion properties of an ultrathin spoof plasmonic waveguide based on metal strip grooves using the finite element method. The confinement ability of the surface plasmon polariton (SPP) waves are influenced by the dispersion curves, which can be modulated by the structure parameters. The propagation characteristics of a subwavelength planar plasmonic waveguide ring resonator have also been studied. Furthermore, a gain medium is introduced to compensate for the propagation loss of the SPP wave in the device at terahertz frequency. It is demonstrated that the gain medium provides an enhancement for the control of on/off states of the signal with the presence of pumping, which paves a way for gain-assisted switching and lasing applications in the terahertz regime.

Yan Liu;Jing Yan;Yao Shao;Jie Pan;Chunfu Zhang;跃 郝;Genquan Han

Applied Optics

2016-3-1

The growth of high-performance Mg-doped p-type Al_xGa _1-xN (x 0.2) using metal-organic chemical vapor deposition is reported. The influence of growth conditions (growth temperature, magnesium flow, and thermal annealing temperature) on the electrical properties of Mg-doped p-type Al_xGa_1-xN (x 0.2) has been investigated. Using the optimized conditions, we obtained a minimum p-type resistivity of 0.71 Ωcm for p-type AlGaN with 20% Al fraction.

Xiaowei Zhou;培咸 李;Shengrui Xu;跃 郝

Journal of Semiconductors

2009

The conventional AlGaN/GaN high electron mobility transistor (HEMT), the AlGaN/GaN/AlGaN HEMT, and the Al_xGa_1-xN/Al _yGa_1-yN HEMT are fabricated on sapphire substrates to study the drain-induced barrier-lowering (DIBL) effect. It is found that the Al_xGa_1-xN/Al_yGa_1-yN HEMT with AlGaN channel has the lowest DIBL coefficient of 6.7 mV/V compared with the other two HEMTs. This is attributed to the best two-dimensional electron gas confinement of the Al_xGa_1-xN/Al_yGa_1-yN structure. This opinion is further confirmed by the conduction band diagrams and electron distribution calculated from the one-dimensional Poisson - Schrödinger equation.

Wei Ha;进成 张;Sheng Lei Zhao;Sha Sha Ge;Hui Juan Wen;Chun Fu Zhang;Xiao Hua Ma;跃 郝

Chinese Physics Letters

2013-12

To improve the performance and reliability of grooved gate MOSFETs, the effects of a concave corner on the characteristics of deep sub-micrometre grooved-gate PMOSFETs are studied using the device simulator MEDICI. The results of our study indicate that the concave corner of a recessed gate influences device characteristics strongly. With an increase of the concave corner, the threshold voltage increases, the current driving capability is improved and the hot-carrier effect is decreased.

H. Ren;跃 郝

Semiconductor Science and Technology

2001-5

Negative bias temperature instability (NBTI) and stress-induced leakage current (SILC) both are more serious due to the aggressive scaling lowering of devices. We investigate the SILC during NBTI stress in PMOSFETs with ultra-thin gate dielectrics. The SILC sensed range from -1 V to 1 V is divided into four parts: the on-state SILC, the near-zero SILC, the off-state SILC sensed at lower positive voltages and the one sensed at higher positive voltages. We develop a model of tunnelling assisted by interface states and oxide bulk traps to explain the four different parts of SILC during NBTI stress.

艳荣 曹;跃 郝;Xiao Hua Ma;Lei Yu;Shi Gang Hu

Chinese Physics Letters

2008-4-1