Monolayer MoS 2 photodetectors with a buried-gate field-effect transistor structure.

Unlike zero-bandgap graphene, molybdenum disulfide (MoS ₂ ) has an adjustable bandgap and high light absorption rate, hence photodetectors based on MoS ₂ have attracted tremendous research attention. Most of the reported MoS ₂ photodetectors adopted back-gate field-effect transistor (FET) structure due to its easy fabrication and modulation features. However, the back-gate FET structure requires very high gate voltage up to 100 V, and it is impossible to modulate each device in an array with this structure independently. This work demonstrated a monolayer MoS ₂ photodetector based on a buried-gate FET structure whose experimental results showed that both the electrical and photoelectrical properties could be well modulated by a gate voltage as low as 3 V. A photoresponsivity above 1 A W ^-1 was obtained under a 395 nm light-emitting diode light illumination, which is over 2 orders of magnitude higher than that of a reported back-gate photodetector based on monolayer MoS ₂ (7.5 mA W ^-1 ). The photoresponsivity can be further improved by increasing the buried gate voltage and source-drain voltage. These results are of significance for the practical applications of MoS ₂ photodetectors, especially in the low voltage and energy-saving areas.
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