Highly tunable quantum Hall far-infrared photodetector by use of GaAs/AlxGa1-xAs-graphene composite material.

We have developed a highly tunable, narrow band far-infrared (FIR) photodetector which utilizes the characteristic merits of graphene and two-dimensional electron gas (2DEG) in GaAs/Al_xGa_1-xAs heterostructure in the Quantum Hall states (QHS). The heterostructure surface is covered with chemi-cal vapor-deposited graphene, which functions as a transparent top-gate to vary the electron density of the 2DEG. FIR response observed in the vicinity of integer QH regime can be effectively tuned in a wide range of 27-102 cm_1 with a bias voltage less than _ 1 V. In addition, we have found that the presence of graphene can genuinely modulate the photoresponse. Our results demonstrate a promis-ing direction for realizing a tunable long-wavelength FIR detector using QHS in GaAs 2DEG/ graphene composite material. [ABSTRACT FROM AUTHOR]