基于石墨烯场效应管的太赫兹天文探测器研究

太赫兹波具有带宽大、能量适中等特点，在材料科学、光学通讯、环境监测、国土安全等领域具有重要的科学研究价值和广阔的应用前景。重要地是，太赫兹波段涵盖了超过一半的宇宙空间光子、星际分子及冷暗天体的辐射特征，因此在射电天文领域具有非常独特的研究价值。传统天文领域探测太赫兹辐射的方法一般利用肖特基二极管、超导-绝缘体-超导隧穿结以及热电子辐射热计等混频器件进行外差式探测，然而，这些探测器要么受限于较低的探测频率，要么需要在极严苛的环境温度下工作。因此，本项目的研究目标就是进行新型太赫兹探测器的机理研究和器件开发。我们准备利用石墨烯这种新型二维电子气作为场效应晶体管的沟道，利用沟道中可调谐的等离子体波（即电子密度波）对外界太赫兹辐射的整流效应，通过测量晶体管源漏极间的直流电学特性来实现频率可调谐、高灵敏度的太赫兹探测目的。研究预计将在包括射电天文领域在内的许多领域具有非常广阔的应用前景。

Terahertz wave, due to its characteristics including broadband and moderate energy, is of great scientific importance and wide application prospects in various fields such as materials science, optical communication, environmental monitoring, and homeland security. Importantly, terahertz radiation has quite unique values in radio astronomical observation in that more than one half space radiation from cosmos, interstellar molecules, and cold dark celestial bodies has such ‘fingerprint’ characteristics. Traditionally, heterodyne techniques are applied for the terahertz photomixers mediated by Schottky diode (SD), superconductor-insulator-superconductor (SIS), or hot-electron bolometer (HEB). However, these are either hampered by the low working frequency or constrained by the cryogenic working temperature. This proposal aims at the mechanism investigations and application fabrications of novel terahertz detectors. We propose that the terahertz radiation detection can be achieved by using two-dimensional plasma waves (electron density wave) propagating in the graphene channel of field-effect transistor (FET). The d.c. signals induced by the rectification of nonlinear plasma transfer between the source and drain in the FET are used to characterize the terahertz radiation, inspiring the novel exploration of frequency-tunable, highly sensitive terahertz detectors. Such investigations and applications will surely bring great prospects in various fields, especially in radio astronomy.