Room‐Temperature Self‐Powered Terahertz Photodetection in Ge‐Intercalated Topological Insulator GeBi₄Te₇

Abstract

Topological insulators (TIs) are under rapid and intensive study in the fields of condensed matter physics, due to exotic electronic properties. Recent studies of photocurrent generation in topological surface states (TSS) properties have insufficient evidence to rule out that of bulk states, hindering the application in optoelectronics. Herein, the chemical vapor transport (CVT) synthesis of GeBi4Te7 crystal by the way of Ge intercalation is realized, enabling isolated Dirac points‐associated high‐mobility Dirac carriers and larger Seebeck coefficients. Then, the antenna‐coupled photodetector in GeBi4Te7 based on planar metal–TI–metal structure is reported, successfully realizing sensitive terahertz response without bias. According to the results, the GeBi4Te7‐based terahertz photodetector has a short response time and a high photoresponsivity (0.42 A W−1 at 0.107 THz and 0.6 A W−1 at 0.28 THz, respectively). The GeBi4Te7–graphene heterostructure can further improve the responsivity by more than two orders of magnitude, reaching 12 A W−1 at 0.107 THz. These findings bring up doable avenues for GeBi4Te7 materials’ low‐energy optoelectronic applications.