Recently GaN-based high electron mobility transistors （HEMTs） have revealed the superior properties of a high breakdown field and high electron saturation velocity. Reduction of the gate leakage current is one of th...Recently GaN-based high electron mobility transistors （HEMTs） have revealed the superior properties of a high breakdown field and high electron saturation velocity. Reduction of the gate leakage current is one of the key issues to be solved for their further improvement. This paper reports that an Al layer as thin as 3 nm was inserted between the conventional Ni/Au Schottky contact and n-GaN epilayers, and the Schottky behaviour of Al/Ni/Au contact was investigated under various annealing conditions by current-voltage （I-V） measurements. A non-linear fitting method was used to extract the contact parameters from the I-V characteristic curves. Experimental results indicate that reduction of the gate leakage current by as much as four orders of magnitude was successfully recorded by thermal annealing. And high quality Schottky contact with a barrier height of 0.875 eV and the lowest reverse-bias leakage current, respectively, can be obtained under 12 min annealing at 450 ℃ in N2 ambience.展开更多
The Pt/Si/Ta/Ti multilayer metal contacts on 4H-Si C are annealed in Ar atmosphere at 600°C-1100°C by a rapid thermal processor（RTP）. The long-term thermal stability is evaluated by aging the annealed cont...The Pt/Si/Ta/Ti multilayer metal contacts on 4H-Si C are annealed in Ar atmosphere at 600°C-1100°C by a rapid thermal processor（RTP）. The long-term thermal stability is evaluated by aging the annealed contact at 600°C in air. The contact＇s properties are determined by current-voltage measurement, and the specific contact resistance is calculated based on the transmission line model（TLM）. Transmission electron microscope（TEM） and energy-dispersive x-ray spectrometry（EDX） are used to characterize the interface morphology, thickness, and composition. The results reveal that a higher annealing temperature is favorable for the formation of an Ohmic contact with a lower specific contact resistance, and causes the rapid degradation of the Ohmic contact in the aging process.展开更多
Development of graphene field effect transistors （GFETs） faces a serious challenge of graphene interface to the dielectric material. A single layer of intrinsic graphene has an average sheet resistance of the order ...Development of graphene field effect transistors （GFETs） faces a serious challenge of graphene interface to the dielectric material. A single layer of intrinsic graphene has an average sheet resistance of the order of 1-5 kΩ/□. The intrinsic nature of graphene leads to higher contact resistance yielding into the outstanding properties of the material. We design a graphene matrix with minimized sheet resistance of 0.185 kΩ/□ with Ag contacts. The developed matrices on silicon substrates provide a variety of transistor design options for subsequent fabrication. The graphene layer is developed over 400 nm nickel in such a way as to analyze hypersensitive electrical properties of the interface for exfoliation. This work identifies potential of the design in the applicability of few-layer GFETs with less process steps with the help of analyzing the effect of metal contact and post-process anneMing on its electrical fabrication.展开更多
采用电子束蒸发工艺在GaAs基LED外延层上制备了氧化铟锡(ITO:Indium Tin Oxide)薄膜,采用快速热退火(RTA:Rapid Thermo Annealing)工艺制备ITO薄膜与GaAs外延层的欧姆接触。研究了退火温度、退火时间对ITO薄膜性能以及LED芯片性能的影...采用电子束蒸发工艺在GaAs基LED外延层上制备了氧化铟锡(ITO:Indium Tin Oxide)薄膜,采用快速热退火(RTA:Rapid Thermo Annealing)工艺制备ITO薄膜与GaAs外延层的欧姆接触。研究了退火温度、退火时间对ITO薄膜性能以及LED芯片性能的影响。结果显示:固定退火时间8s时,ITO薄膜方块电阻呈减小趋势,但变化不大,430℃时为7.7Ω/□;LED芯片亮度LOP呈现非线性先上升后下降趋势,430℃时达峰值136mcd;外延片背面欧姆电阻呈现先下降后上升抛物线趋势,440℃时达谷值1.13Ω。固定退火温度415℃时,LED芯片亮度LOP呈现非线性先上升后下降趋势,退火12s时达峰值132.5mcd;外延片背面欧姆电阻呈现先下降后上升抛物线趋势,退火12s时时达谷值0.93Ω。展开更多
文摘Recently GaN-based high electron mobility transistors （HEMTs） have revealed the superior properties of a high breakdown field and high electron saturation velocity. Reduction of the gate leakage current is one of the key issues to be solved for their further improvement. This paper reports that an Al layer as thin as 3 nm was inserted between the conventional Ni/Au Schottky contact and n-GaN epilayers, and the Schottky behaviour of Al/Ni/Au contact was investigated under various annealing conditions by current-voltage （I-V） measurements. A non-linear fitting method was used to extract the contact parameters from the I-V characteristic curves. Experimental results indicate that reduction of the gate leakage current by as much as four orders of magnitude was successfully recorded by thermal annealing. And high quality Schottky contact with a barrier height of 0.875 eV and the lowest reverse-bias leakage current, respectively, can be obtained under 12 min annealing at 450 ℃ in N2 ambience.
基金Project supported by the Special Prophase Project on the National Basic Research Program of China(Grant No.2012CB326402)the National Natural Science Found of China(Grant No.61404085)+1 种基金the Innovation Program of Shanghai Municipal Education Commission,China(Grant No.13ZZ108)the Shanghai Science and Technology Commission,China(Grant No.13520502700)
文摘The Pt/Si/Ta/Ti multilayer metal contacts on 4H-Si C are annealed in Ar atmosphere at 600°C-1100°C by a rapid thermal processor（RTP）. The long-term thermal stability is evaluated by aging the annealed contact at 600°C in air. The contact＇s properties are determined by current-voltage measurement, and the specific contact resistance is calculated based on the transmission line model（TLM）. Transmission electron microscope（TEM） and energy-dispersive x-ray spectrometry（EDX） are used to characterize the interface morphology, thickness, and composition. The results reveal that a higher annealing temperature is favorable for the formation of an Ohmic contact with a lower specific contact resistance, and causes the rapid degradation of the Ohmic contact in the aging process.
文摘Development of graphene field effect transistors （GFETs） faces a serious challenge of graphene interface to the dielectric material. A single layer of intrinsic graphene has an average sheet resistance of the order of 1-5 kΩ/□. The intrinsic nature of graphene leads to higher contact resistance yielding into the outstanding properties of the material. We design a graphene matrix with minimized sheet resistance of 0.185 kΩ/□ with Ag contacts. The developed matrices on silicon substrates provide a variety of transistor design options for subsequent fabrication. The graphene layer is developed over 400 nm nickel in such a way as to analyze hypersensitive electrical properties of the interface for exfoliation. This work identifies potential of the design in the applicability of few-layer GFETs with less process steps with the help of analyzing the effect of metal contact and post-process anneMing on its electrical fabrication.
基金Advanced Research Foundation of China(914xxx803-051xxx111)National Defense Advanced Research project(315xxxxx301)National Defense Innovation Program(48xx4).
文摘采用电子束蒸发工艺在GaAs基LED外延层上制备了氧化铟锡(ITO:Indium Tin Oxide)薄膜,采用快速热退火(RTA:Rapid Thermo Annealing)工艺制备ITO薄膜与GaAs外延层的欧姆接触。研究了退火温度、退火时间对ITO薄膜性能以及LED芯片性能的影响。结果显示:固定退火时间8s时,ITO薄膜方块电阻呈减小趋势,但变化不大,430℃时为7.7Ω/□;LED芯片亮度LOP呈现非线性先上升后下降趋势,430℃时达峰值136mcd;外延片背面欧姆电阻呈现先下降后上升抛物线趋势,440℃时达谷值1.13Ω。固定退火温度415℃时,LED芯片亮度LOP呈现非线性先上升后下降趋势,退火12s时达峰值132.5mcd;外延片背面欧姆电阻呈现先下降后上升抛物线趋势,退火12s时时达谷值0.93Ω。
