Study on Optically Injection-Locked Terahertz Oscillation in Plasma-Wave Resonant Transistors

我们研究了等离子体波晶体管(PWT)的光注入锁定太赫兹振荡的可能性。PWT是一种利用场效应晶体管(FET)沟道中高密度二维传导电子的等离子体共振效应的新型电子器件。谐振频率可以由栅极偏置电势外部控制，从而提供了振荡的稳定性。首先，对亚100 nm GaAs MESFET的等离子体共振现象进行了实验研究。太赫兹激发是通过以差频产生的方式将两个激光源光混合来执行的。光学注入锁定等离子体谐振调制直流漏源电势。因此，可以通过监控DC调制分量ΔVds来测量谐振强度。在几种不同频率条件下测量了ΔVDS的栅偏压依赖关系。结果清楚地表明血浆反应性…的发生。在太赫兹范围内有更多的声音。首次验证了在较宽的太赫兹范围内，等离子体谐振频率受栅极偏置的外部控制。接下来，我们首次观测到了0.15μm栅长的InGaP/InGaAs/GaAs赝晶HEMT(PHEMT)的等离子体共振强度随频率的变化规律。当适当地施加栅偏压以在沟道中诱导足够密度的电子时，可以清楚地观察到双峰共振。1.9太赫兹处的第一个峰对应于基波共振，而5.8太赫兹处的第二个峰对应于三次简谐共振。观察到的共振频率与理论计算吻合得很好。探测到的等离子体共振实际上是非辐射模式振荡，在毫瓦级激发功率下，其能量估计在北纬数量级。应该在器件结构上采用将等离子体振荡转换为电磁辐射的手段。此外，提高量子效率也是关键。这些都是未来的主题。较少

We have studied the possibility of optically injection-locked terahertz oscillations of the plasma-wave transistors (PWT's). The PWT is a new type of the electron device that utilizes the plasma resonance effect of highly dense two-dimensional conduction electrons in the field effect transistors (FET) channel. The resonance frequency can be externally controlled by the gate bias potential, which offers the tenability of oscillation. First, the plasma resonant phenomena were experimentally investigated for a sub-100-nm GaAs MESFET. The terahertz excitation was performed by photomixing the two laser sources in a manner of difference-frequency generation. The optically injection-locked plasma resonance modulates the DC drain-source potential. The resonant intensity, thus, can be measured by monitoring the DC modulation component : ΔVds. The gate-bias dependence of ΔVds was measured under several, difference-frequency conditions. The results clearly indicated the occurrence of plasma reson … More ance in the terahertz range. It was verified for the first time that the plasma resonance frequency is controlled externally by the gate bias in a wide terahertz range. Next, we have carried on the first observation of the frequency dependence of the plasma resonant intensity for a 0.15-μm gate-length InGaP/InGaAs/GaAs pseudomorphic HEMT (pHEMT). When the gate bias was properly applied to induce a sufficient density of electrons in the channel, the resonance was clearly observed with a double peak. The first peak at 1.9 THz corresponds to the fundamental resonance while the second peak at 5.8 THz corresponds to the third harmonic resonance. Observed resonant frequencies coincided well -to the theoretical calculation. The detected plasma resonances are actually non-radiative-mode oscillation and their energy is estimated to be on the order of nW under mW excitation power. A mean to convert the plasma oscillation to an electromagnetic radiation should be employed onto the device structure. Also, improvement of the quantum efficiency is the key.' These are the future subjects. Less