[15a-2D-1~8] 4.6 Nanocarbon and 2D materials photonics

▼ [15a-2D-6] Resonant Emission and Detection of Terahertz Radiation from
Double Graphene Layer Heterostructures

〇(D)Deepika Yadav¹, Stevanus Arnold¹, Stephane Boubanga Tombet¹, Takayuki Watanabe¹, Victor Ryzhii^1,2, Taiichi Otsuji¹ (1.RIEC, Tohoku Univ., Japan, 2.Inst. of Ultra-High-Freq. Semic. Elec., Russia)

Keywords:Graphene,Terahertz,Resonant tunneling

Double-graphene-layer (DGL) heterostructures have recently been investigated in a number of experimental and theoretical works due to their various potential applications in optical modulation, terahertz (THz) emission/detection, and THz photo-mixing [1] and many more. Here, we report on experimental observation of the THz emission and detection in the DGL structures and demonstrate that the photon-assisted resonant radiative inter-GL transitions enable the applications of such devices for THz lasers and photodetectors (PDs) [2].
The fabricated devices consist of a thin h-BN tunnel-barrier sandwiched between two crystallographic ally aligned graphene layers. The bias voltage V applied between the GL’s contacts induces the electron gas in one and hole gas in the other GL forming a DGL capacitor. The electron and hole densities in GLs are also controlled by the gate voltage Vg. The voltage-dependent band-offset energy (Δ) between the Dirac points of the GLs and the depolarization shift determine the energies of the photons emitted (in the lasers) or absorbed (in the PDs) in the resonant-tunneling inter-GL transitions[3]. The tunneling causes all excess charges in the n-type GL to recombine with the holes in the p-type GL.