Signal-to-noise characteristics of graphene photodetectors based on photothermoelectric effect

Abstract

A sensor using the photothermoelectric effect of graphene is anticipated as a candidate for infrared sensors that can operate at room temperature with fast response and high sensitivity. We investigate photothermoelectric detection and the signal-to-noise characteristics of a sensor with a simple metal-graphene-metal structure numerically and analytically and obtain an analytical expression giving the ideal value of specific detectivity D ∗ - for a sensor having an ideal potential distribution. It is found that the optimal sensor length is approximately three times longer than the cooling length and that the value of D ∗ - for such a sensor with typical cooling length is estimated to be as large as 106 cm Hz / W. The sensor performance can be greatly enhanced by employing light-confining structures such as cavities and plasmon antennas, achieving D ∗ - above 108 cm Hz / W.