Patent ID: 8093633
Filing Date: 2012-01-10
Classification: H01L,Y02E

Abstract:
1. A method of photo-sensing comprising: biasing a junction field effect transistor (JFET) to generate a conducting channel between a source and a drain of said JFET, said conducting channel having an absorption section below a light-transmitting surface of said JFET, said absorption section having a pre-determined photo-conductivity spectral response, and at least two depleted regions below said light-transmitting surface, each having a photo-electric spectral response peaking at a distinct, pre-determined wavelength; illuminating said light-transmitting surface with light; sensing an output signal derived from said channel indicative of the intensity of light absorbed therein; and for each particular one of said depleted regions, sensing an output signal derived from said particular depleted region indicative of the intensity of light absorbed therein, wherein said one or more depleted regions comprise two depleted regions at different depths below said light-transmitting surface; wherein said sensing an output signal comprises sensing a drain-source current from said drain to said source through said conducting channel, and wherein said sensing an output signal derived from said particular depleted region comprises sensing a gate current from a gate in contact with said particular depleted region; and wherein said sensing a drain-source current comprises: sensing a drain-source photo-induced current variation based on: sensing a drain current from said drain during said illuminating, obtaining a quiescent drain-source current, and calculating said photo-induced drain-source current variation by subtracting from said drain current said quiescent drain-source current and the sum of said gate currents.