Noise behavior of an optically controlled GaAs MESFET

The noise behavior of an optically controlled metal-semiconductor field-effect transistor (OPFET) is investigated theoretically. A rigorous model has been developed for computation of different noise components in OPFET. The intrinsic parameters of the metal-semiconductor-field-effect transistor (MESFET) equivalent circuit are strongly influenced by the incident optical signal, and the photogenerated carriers are found to play a significant role in deciding the overall noise performance of an OPFET. The study also reveals that the operating frequency can be adjusted suitably to make the noise behavior of the OPFET independent of the value of the incident optical power. The device exhibits a high value of noise equivalent power (NEP) that may make it less attractive for application as a photodetector.