分类: 材料科学 >> 纳米科学和纳米技术 提交时间: 2016-12-23
摘要: A novel double gate AlGaN/GaN HEMT, in which an additional top-gate covers the adjacent regions of normal gate, was proposed and fabricated for the first time to compare the dynamic characteristics of AlGaN/GaN HEMTs with source field plate(SFP) and gate field plate(GFP). During the dynamic characterization, the device was configured in two operation modes, one is the source-field-plate mode (SFP-mode) with the top gate biased at 0V, another is the gate-field-plate mode (GFP-mode) with applying the gate pulse signal on the top gate at the same time. Compared to an AlGaN/GaN HEMT without field plates, both GFP and SFP much improve the dynamic performances. Compared to SFP, the GFP shows better dynamic performances with a ~34% reduction of switch-on delay time and ~6% reduction of dynamic on-resistance. By study of the dynamic characteristics with applying negative voltage on the top gate during off-state, the mechanism differences between GFP and SFP are discussed in detail.
分类: 材料科学 >> 纳米科学和纳米技术 提交时间: 2016-12-22
摘要: This paper presents a fabrication technology of enhancement-mode (E-mode) AlGaN/GaN metal insulator semiconductor high electron-mobility transistors (MIS-HEMTs) using 10 keV fluorine ion implantation. An 8 nm low pressure chemical vapor deposition (LPCVD) silicon nitride layer was deposited on the AlGaN as gate dielectric and energy-absorbing layer that slows down the high energy (10 keV) fluorine ions to reduce the implantation damage. The E-mode MIS-HEMTs exhibit a threshold voltage as high as 3.3 V with a maximum drain current over 200 mA/mm (250 mA/mm for depletion-mode (D-mode) MIS-HEMTs) and a high on/off current ratio of 109. Meanwhile, the E-mode MIS-HEMTs dynamic RON is only 1.53 times than the static RON after off-state VDS stress of 500 V.
分类: 工程与技术科学 >> 物理学相关工程与技术 分类: 工程与技术科学 >> 仪器仪表技术 分类: 电子与通信技术 >> 电子技术 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2024-05-06
摘要: 本文提出了一种用于低温扫描隧道显微镜(CryoSTM)的跨阻放大器(TIA)设计方案。在CryoSTM中带有尖端样品成分的TIA称为CryoSTM-TIA。该CryoSTM-TIA的跨阻增益在1Gohm,而其带宽大于300kHz。所提出的CryoSTM-TIA的独特特点是其前置放大器由单个低温高电子迁移率晶体管(HEMT)制成,因此在100kHz时仪器等效输入噪声电流功率谱密度低于4(fA)2/Hz。此外,应用“偏置冷却法”可用于原位控制HEMT掺杂区冻结DX-中心的密度,改变其结构以降低器件噪声。利用该仪器,可以进行高能量分辨率的快速扫描隧道光谱测量。并且,它能够测量各种量子系统在原子尺度上的扫描隧道散粒噪声谱(STSNS),即使散粒噪声非常低。它为通过测量STSNS来研究新的量子态提供了一个强大的工具,例如检测拓扑量子系统中马约拉纳束缚态的存在。
分类: 工程与技术科学 >> 物理学相关工程与技术 分类: 工程与技术科学 >> 仪器仪表技术 分类: 电子与通信技术 >> 电子技术 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2022-12-29
摘要: 提出了一种用于低温扫描隧道显微镜(CryoSTM)的低噪声高增益大带宽跨阻放大器(TIA)。在CryoSTM中与尖端样品组件连接的TIA称为CryoSTM-TIA。CryoSTM-TIA的跨阻增益为10Gohm,带宽超过100kHz,在100kHz时等效输入噪声电流功率谱密度小于4(fA)2/Hz。CryoSTM-TIA的低固有噪声是由于其特殊的设计: (1)其前置放大器(Pre-Amp)由低噪声低温高电子迁移率晶体管制成; (2)前置放大器采用卡片式配置,避免米勒效应,降低输入电容CA; (3)将前置放大器输入端连接到尖端的电缆的电容,即CI最小化; (4)热噪声源,如反馈电阻,放置在低温区。由于在反馈回路中应用了频率补偿,减小了CA,减小了CI,实现了高增益和大带宽。该仪器可用于低电导率材料扫描隧道光谱的快速高能量分辨率测量,特别是用于测量其扫描隧道发射噪声谱。