Efetov Dmitri K, Shiue Ren-Jye, Gao Yuanda, Skinner Brian, Walsh Evan D, Choi Hyeongrak, Zheng Jiabao, Tan Cheng, Grosso Gabriele, Peng Cheng, Hone James, Fong Kin Chung, Englund Dirk
ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain.
Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA, USA.
Nat Nanotechnol. 2018 Sep;13(9):797-801. doi: 10.1038/s41565-018-0169-0. Epub 2018 Jun 11.
High sensitivity, fast response time and strong light absorption are the most important metrics for infrared sensing and imaging. The trade-off between these characteristics remains the primary challenge in bolometry. Graphene with its unique combination of a record small electronic heat capacity and a weak electron-phonon coupling has emerged as a sensitive bolometric medium that allows for high intrinsic bandwidths. Moreover, the material's light absorption can be enhanced to near unity by integration into photonic structures. Here, we introduce an integrated hot-electron bolometer based on Johnson noise readout of electrons in ultra-clean hexagonal-boron-nitride-encapsulated graphene, which is critically coupled to incident radiation through a photonic nanocavity with Q = 900. The device operates at telecom wavelengths and shows an enhanced bolometric response at charge neutrality. At 5 K, we obtain a noise equivalent power of about 10 pW Hz, a record fast thermal relaxation time, <35 ps, and an improved light absorption. However the device can operate even above 300 K with reduced sensitivity. We work out the performance mechanisms and limits of the graphene bolometer and give important insights towards the potential development of practical applications.
高灵敏度、快速响应时间和强光吸收是红外传感与成像的最重要指标。这些特性之间的权衡仍然是测辐射热技术的主要挑战。石墨烯具有创纪录的小电子热容量和弱电子-声子耦合的独特组合，已成为一种灵敏的测辐射热介质，可实现高本征带宽。此外，通过集成到光子结构中，该材料的光吸收可增强至接近100%。在此，我们介绍一种基于超清洁六方氮化硼封装石墨烯中电子的约翰逊噪声读出的集成热电子测辐射热计，它通过品质因数Q = 900的光子纳米腔与入射辐射实现关键耦合。该器件在电信波长下工作，在电荷中性时表现出增强的测辐射热响应。在5K时，我们获得了约10 pW/Hz的噪声等效功率、创纪录的快速热弛豫时间（<35 ps）以及改善的光吸收。然而，该器件甚至在300K以上也能工作，只是灵敏度有所降低。我们研究了石墨烯测辐射热计的性能机制和极限，并为实际应用的潜在发展提供了重要见解。
