研究目的
Investigating the light-induced charge transfer at the interface of graphene/InSe heterostructures and its effects on the electronic properties of graphene.
研究成果
The study demonstrates novel hybrid InSe/graphene phototransistor devices where the electronic properties of the graphene layer can be controlled by a combination of field effect gating and the transfer of photoexcited carriers across the InSe-graphene interface. The light-induced charge transfer induces a reversal of the sign of the Hall voltage and of the h/2e2 quantum Hall plateau, which extends over a wide range of applied magnetic fields and temperatures. These findings highlight the potential of light-induced charge transfer in gate-tunable InSe/graphene phototransistors for optoelectronics and quantum metrology.
研究不足
The response time of the photocurrent is relatively slow and is partly limited by charge traps and the RC time of the device structures. The study is conducted under quasistatic conditions, and dynamic polarization effects are not considered.
1：Experimental Design and Method Selection:
The study involves the fabrication of field effect phototransistors where single layer graphene is capped with n-type InSe. The methodology includes optical and magneto-transport studies to probe the charge transfer at the InSe/graphene interface.
2：Sample Selection and Data Sources:
High quality InSe flakes were exfoliated from a Bridgman-grown InSe crystal and transferred to a graphene Hall bar. The graphene was grown by CVD on a copper foil substrate and transferred to a SiO2/p-Si substrate.
3：List of Experimental Equipment and Materials:
A superconducting magneto-cryostat for magneto-transport measurements, a He-Ne laser for optical illumination, and a focused laser beam for photoconductivity mapping experiments.
4：Experimental Procedures and Operational Workflow:
The magneto-transport measurements were performed at magnetic fields up to 14T or 25T and over a range of gate voltages. For the magneto-transport experiments under optical illumination, an unfocused He-Ne laser beam was used.
5：Data Analysis Methods:
The data analysis involved calculating the carrier density in the graphene and InSe layers under optical excitation and estimating the photoresponsivity of the devices.
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