Observation of well-defined Kohn-anomaly in high-quality graphene devices at room temperature
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Universidade Federal de Minas Gerais
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Artigo de periódico
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Due to its ultra-thin nature, the study of graphene quantum optoelectronics, like gate-dependent graphene Raman properties, is obscured by interactions with substrates and surroundings. For instance, the use of doped silicon with a capping thermal oxide layer limited the observation to low temperatures of a well-defined Kohn-anomaly behavior, related to the breakdown of the adiabatic Born–Oppenheimer approximation. Here, we design an optoelectronic device consisting of single-layer graphene electrically contacted with thin graphite leads, seated on an atomically flat hexagonal boron nitride substrate and gated with an ultra-thin gold layer. We show that this device is optically transparent, has no background optical peaks and photoluminescence from the device components, and no generation of laser-induced electrostatic doping (photodoping). This allows for room-temperature gate-dependent Raman spectroscopy effects that have only been observed at cryogenic temperatures so far, above all the Kohn-anomaly phonon energy normalization. The new device architecture, by decoupling graphene optoelectronic properties from the substrate effects, allows for observing quantum phenomena at room temperature.
Abstract
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Grafeno, Efeito de Raman, Optoeletrônica
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Devices, Room temperature, Graphene, Photodoping, Raman, Optoelectronics, Kohn-anomaly
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https://iopscience.iop.org/article/10.1088/2053-1583/ac8e7f