An improved model for non-resonant terahertz detection in field-effect transistors
An improved model for non-resonant terahertz detection in field-effect transistors
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DOI：
10.1063/1.3676211
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发表时间：
2012-01-15
影响因子：
3.2
通讯作者：
Gossard, A. C.
中科院分区：
文献类型：
--
作者：
Preu, S.;Kim, S.;Gossard, A. C.
晶体管在其增益频率以上工作时仍然可以整流太赫兹电流和电压，并作为室温太赫兹探测器引起了人们的兴趣。我们表明，这样的整流场效应晶体管仍然可以被视为一个集总元件设备中的限制，其中等离子体共振的电子气体不发生。我们推导出重要的晶体管参数的解析公式，如有效整流长度和器件阻抗使用传输线模型。在可能的情况下，我们得出结论等离子体共振检测。通过对漏源偏压的泰勒展开，我们推导出了具有二维电子气通道的场效应晶体管的太赫兹响应。我们将电路理论与用微分方程描述门控区偏置的现有理论联系起来。寄生效应，如接入电阻，包括在内。与本文提出的方法，我们推导出一种新的场探测器，混合（太赫兹）信号施加在栅极和源极之间的漏极和源极之间的零差或外差操作模式的响应。我们进一步推导出预期的噪声等效功率（NEP）在直接检测和混合模式，包括寄生效应的表达式，并发现子pW/根Hz可实现的现实设备和材料参数直接检测和小于900 K的噪声温度混合在10 μ W本地振荡器功率。(C)2012年美国物理学会。[doi 10.1063/1.3676211]
Transistors operating well above the frequencies at which they have gain can still rectify terahertz currents and voltages, and have attracted interest as room-temperature terahertz detectors. We show that such rectifying field-effect transistors may still be treated as a lumped element device in the limit where plasma resonances of the electron gas do not occur. We derive analytic formulas for important transistor parameters, such as effective rectification length and device impedance using a transmission-line model. We draw conclusions for plasma-resonant detection where possible. We derive the THz response of a field-effect transistor with a two-dimensional electron-gas channel by a Taylor expansion of the drain-source bias. We connect circuit theory to the existing theories that describe the bias in the gated region by differential equations. Parasitic effects, such as the access resistance, are included. With the approach presented in this paper, we derive the responsivity for a novel field detector that mixes a (THz) signal applied between gate and source with another signal applied between drain and source in homodyne or heterodyne operation mode. We further derive expressions for the expected noise-equivalent power (NEP) in direct detection and mixing mode, including parasitic effects, and find that sub-pW/root Hz achievable for realistic device and material parameters for direct detection and less than 900K noise temperature for mixing at 10 mu W local oscillator power. (C) 2012 American Institute of Physics. [doi: 10.1063/1.3676211]