Noise and THz rectification characteristics of zero-bias quantum tunneling Sb-heterostructure diodes

The Sb-heterostructure quantum tunneling diode, fabricated from epitaxial layers of InAs and AlGaSb, is a recently proposed device for direct detection and mixing in the submillimeter wavelength range. These diodes exhibit especially high curvature in the current-voltage characteristic that produces the rectification or mixing without bias. Operation without bias is a highly desirable feature as the device does not suffer from large 1/f noise, a major shortcoming in other devices such as Schottky barrier diodes or resistive room temperature bolometers. In this paper we present the noise characteristics of the diode as a function of the bias voltage. At room temperature and zero bias, the device demonstrates a Johnson noise limited intrinsic noise equivalent power of 1 pW/Hz/sup 1/2 /. In addition to the noise measurements, we present the detection characteristics of the diode at a frequency of 2.5 THz. The measured THz laser response deviates from conventional theoretical prediction based on pure rectification. The reasons for the discrepancy will be discussed.