Quantum dot photo-field-effect transistor

Abstract

Photo-field-effect transistor devices and associated methods are disclosed in which a photogate, consisting of a quantum dot sensitizing layer, transfers photoelectrons to a semiconductor channel across a charge-separating (type-II) heterointerface, producing a sustained primary and secondary flow of carriers between source and drain electrodes. The light-absorbing photogate thus modulates the flow of current along the channel, forming a photo-field effect transistor.

What is claimed is: 
     
         1 . A photo-field effect transistor device comprising:
 an electrically insulating substrate;   source and drain electrodes provided on said substrate in a spaced relationship;   a carrier-accepting semiconductor channel contacting said substrate between said source and drain electrodes, wherein said carrier-accepting semiconductor channel is in electrical communication with said source and drain electrodes; and   a light absorbing quantum dot sensitizing layer contacting said carrier-accepting semiconductor channel, said quantum dot sensitizing layer producing photo-generated carriers under illumination of light within a selected optical bandwidth;   wherein an interface between said quantum dot sensitizing layer and said carrier-accepting semiconductor channel forms a type II heterojunction configured to inject one type of said photo-generated carriers into said carrier-accepting semiconductor channel, thereby producing primary photocarriers within said carrier-accepting semiconductor channel; and   wherein said carrier-accepting semiconductor channel is characterized by a mobility such that under application of a voltage difference between said source and drain electrodes and under illumination of said quantum dot sensitizing layer, a photocurrent is produced due to injection of the primary photocarriers and recirculation of secondary photocarriers.   
     
     
         2 . A method of generating photoconductive gain in a photo-field effect transistor device according to  claim 1 , the method comprising:
 illuminating said photo-field effect transistor device with light within said selected optical bandwidth, wherein said photo-field effect transistor device is illuminated from a side associated with said quantum dot sensitizing layer;   applying a voltage difference between said source and drain electrodes; and   detecting a resulting photocurrent.