Plasma Instability and Terahertz Generation in HEMTs Due to Electron Transit-Time Effect
Plasma Instability and Terahertz Generation in HEMTs Due to Electron Transit-Time Effect
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由于电子渡越时间效应导致 HEMT 中的等离子体不稳定性和太赫兹产生
DOI：
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发表时间：
2006
影响因子：
0.5
通讯作者：
M. Shur
中科院分区：
文献类型：
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作者：
V. Ryzhii;A. Satou;M. Shur
我们使用开发的器件模型研究高电子迁移率晶体管中电子密度和电场（电子等离子体振荡）的耦合时空变化。太赫兹频率范围内电子等离子体振荡的激发可能会导致太赫兹辐射的发射。在所开发模型的框架中，我们计算了等离子体谐振频率，并找到了等离子体振荡自激（等离子体不稳定性）的条件。我们表明，高电子迁移率晶体管沟道漏极边缘附近的高电场区域中的渡越时间效应可以引起等离子体振荡的自激。结果表明，当高场区域中的电子速度 u d 与门长度 Lg（即逆渡越时间）与门控通道中的电子碰撞频率 v 相比足够大时，等离子体振荡的自激是可能的。所考虑的等离子体不稳定性的渡越时间机制可以叠加在先前预测的 Dyakonov-Shur 机制上，该机制强烈影响不稳定条件，从而影响太赫兹发射。正在考虑的不稳定机制可能有助于揭示最近实验中观察到的高电子迁移率晶体管太赫兹发射的起源。
We study the coupled spatio-temporal variations of the electron density and the electric field (electron plasma oscillations) in high-electron mobility transistors using the developed device model. The excitation of electron plasma oscillations in the terahertz range of frequencies might lead to the emission of terahertz radiation. In the framework of the model developed, we calculate the resonant plasma frequencies and find the conditions for the plasma oscillations self-excitation (plasma instability) We show that the transit-time effect in the high-electric field region near the drain edge of the channel of high-electron mobility transistors can cause the self-excitation of the plasma oscillations. It is shown that the self-excitation of plasma oscillations is possible when the ratio of the electron velocity in the high field region, u d , and the gate length, Lg, i.e., the inverse transit time are sufficiently large in comparison with the electron collision frequency in the gated channel, v. The transit-time mechanism of plasma instability under consideration can superimpose on the Dyakonov-Shur mechanism predicted previously strongly affecting the conditions of the instability and, hence, terahertz emission. The instability mechanism under consideration might shed light on the origin of terahertz emission from high electron mobility transistors observed in recent experiments.