Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Operational analysis of a quantum dot, optically gated, field-effect transistor as a single-photon detector



Eric Gansen, Mary A. Rowe, Marion Greene, Danna Rosenberg, Todd E. Harvey, Mark Su, Robert Hadfield, Sae Woo Nam, Richard Mirin


We report on the operation of a novel single-photon detector, where a layer of self-assembled quantum dots (QDs) is used as an optically addressable floating gate in a GaAs/Al0.2Ga0.8As Δ}-doped field-effect transistor. Photogenerated holes charge the QDs, and subsequently, change the amount of current flowing through the channel by screening the internal gate field. The photoconductive gain associated with this process makes the structure extremely sensitive to light of the appropriate wavelength. We investigate the charge storage and resulting persistent photoconductivity by performing time-resolved measurements of the channel current and of the photoluminescence emitted from the QDs under laser illumination. In addition, we characterize the response of the detector, and investigate sources of photogenerated signals by using the Poisson statistics of laser light. The device exhibits time-gated, single-shot, single-photon sensitivity at a temperature of 4 K. It also exhibits a linear response, and detects photons absorbed in its dedicated absorption layer with an internal quantum efficiency (IQE) of up to 68+or-}18%. Given the noise of the detection system, the device is shown to operate with an IQE of 53+or-}11% and dark counts of 0.003 counts per shot for a particular discriminator level.
IEEE Journal of Selected Topics in Quantum Electronics


Field-effect transistor, quantum dots, quantum optics, single-photon detector


Gansen, E. , Rowe, M. , Greene, M. , Rosenberg, D. , Harvey, T. , Su, M. , Hadfield, R. , Nam, S. and Mirin, R. (2007), Operational analysis of a quantum dot, optically gated, field-effect transistor as a single-photon detector, IEEE Journal of Selected Topics in Quantum Electronics, [online], (Accessed December 3, 2023)
Created June 30, 2007, Updated October 12, 2021