A voltage tunable quantum dot photodetector for terahertz detection

A voltage tunable quantum dot (QD) photodetector for terahertz detection based on intersublevel transitions is proposed. The intersublevels are formed by the lateral electrical confinement applied on quantum wells and the transitions between them can be strongly tuned by the confinement. Under normal incidence, the peak detection wavelengths can be tuned from ∼50 to ∼90 νm (6.0 to ∼3.3 THz) with a gate voltage range of -5 to -2 V. The peak absorption coefficient of detection is in the order of 10³ cm^-1 at 77 K, and the peak detectivity of the photodetector can reach ∼10⁹ cm² Hz^1/2 W^-1. The proposed approach has the advantage of forming a high uniformity of QD effective sizes and provides an alternative way to detect terahertz radiation.