Afalla Jessica, De Los Reyes Alexander, Cabello Neil Irvin, Vistro Victor Dc Andres, Faustino Maria Angela, Ferrolino John Paul, Prieto Elizabeth Ann, Bardolaza Hannah, Catindig Gerald Angelo R, Gonzales Karl Cedric, Mag-Usara Valynn Katrine, Kitahara Hideaki, Somintac Armando S, Salvador Arnel A, Tani Masahiko, Estacio Elmer S
Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8573, Japan.
Research Center for Development of Far Infrared Region, University of Fukui, Fukui, 910-8507, Japan.
Sci Rep. 2020 Nov 16;10(1):19926. doi: 10.1038/s41598-020-76413-7.
We present the implementation of an efficient terahertz (THz) photoconductive antenna (PCA) emitter design that utilizes high mobility carriers in the two-dimensional electron gas (2DEG) of a modulation-doped heterostructure (MDH). The PCA design is fabricated with recessed metal electrodes in direct contact with the 2DEG region of the MDH. We compare the performance of the MDH PCA having recessed contacts with a PCA fabricated on bulk semi-insulating GaAs, on low temperature-grown GaAs, and a MDH PCA with the contacts fabricated on the surface. By recessing the contacts, the applied bias can effectively accelerate the high-mobility carriers within the 2DEG, which increases the THz power emission by at least an order of magnitude compared to those with conventional structures. The dynamic range (62 dB) and bandwidth characteristics (3.2 THz) in the power spectrum are shown to be comparable with the reference samples. Drude-Lorentz simulations corroborate the results that the higher-mobility carriers in the MDH, increase the THz emission. The saturation characteristics were also measured via optical fluence dependence, revealing a lower saturation value compared to the reference samples. The high THz conversion efficiency of the MDH-PCA with recessed contacts at low optical power makes it an attractive candidate for THz-time domain spectroscopy systems powered by low power fiber lasers.
我们展示了一种高效太赫兹（THz）光电导天线（PCA）发射器设计的实现，该设计利用了调制掺杂异质结构（MDH）二维电子气（2DEG）中的高迁移率载流子。PCA设计采用与MDH的2DEG区域直接接触的凹陷金属电极制造。我们将具有凹陷接触的MDH PCA的性能与在体半绝缘砷化镓、低温生长的砷化镓上制造的PCA以及接触在表面制造的MDH PCA进行了比较。通过使接触凹陷，施加的偏压可以有效地加速2DEG内的高迁移率载流子，与传统结构相比，这使太赫兹功率发射增加了至少一个数量级。功率谱中的动态范围（62 dB）和带宽特性（3.2 THz）与参考样品相当。德鲁德 - 洛伦兹模拟证实了MDH中较高迁移率的载流子会增加太赫兹发射的结果。还通过光通量依赖性测量了饱和特性，结果显示与参考样品相比饱和值较低。具有凹陷接触的MDH - PCA在低光功率下的高太赫兹转换效率使其成为由低功率光纤激光器驱动的太赫兹时域光谱系统的有吸引力的候选者。
