Weak-source for cryogenic semiconductor device

Abstract

Abstract A two-gate field-effect transistor (FET) is designed to operate at cryogenic temperatures (circa 1°-20° K.). For an N channel FET, the low-concentration weak-P type material used for the channel region is built into an intrinsic (or near-intrinsic) layer which in turn is built on a P type substrate. The first gate corresponds to a conventional FET control gate. The second gate may be designated a weak-source gate and is directly above a corresponding weak-source region which is itself adjacent to the conventional (strong) source region. The weak-source gate is placed at a fixed positive potential with respect to the source region so that the electrons will collect in the conduction band within the weak-source region. Once the required fixed weak-source gate potential has been established, the control gate functions in a conventional manner even when the device is at a cryogenic temperature. Such a weak-source gate over a weak-source region may be utilized to inject carriers into a charge-coupled device, or any similar device, even at cryogenic temperatures. The device channel region can, alternatively, be made of the same non-conductive low concentration N type material as the weak-source region and can be the same as the material used for the absorption of infrared photons by the associated infrared detectors thus allowing the simultaneous epitaxial construction of both the FET/CCD electronics and the associated infrared detectors.

Inventors

• 👤 Michael A. Levine

Bibliographic Details