A tunable terahertz photodetector based on electrical confinement

The terahertz region in the electromagnetic spectrum has attracted much research interest recently, because of its potential applications in many areas, such as biological and medical imaging, free-space communications, and homeland security. Here, a tunable quantum dot photodetector for terahertz detection based on intersublevel transitions is proposed and simulated. The intersublevels are formed by a lateral electric field confinement on quantum wells. The intersublevel spacing can be tuned and in hence different wavelengths in the terahertz region can be detected. Our simulation results show a tunability of peak detection wavelength from ∼3.3 to ∼12 THz by only changing the electrical confinement voltages and the peak absorption coefficients of the detection are in the range of 10³ cm^-1. The peak calculated detectivity of the tunable photodetector is as big as 1.7×10⁹ Jones. Compared with quantum dot terahertz photodetectors produced by self-assembled growth method, the detector presented here is easier to be tuned and the effective sizes have a much higher uniformity, because of the uniform electrical confinement.