Schottky diodes in CMOS for terahertz circuits and systems

Using Polysilicon Gate Separated Schottky Diode structures that can be fabricated without any process modifications in a foundry digital 130-nm CMOS process, cut-off frequency of ~2 THz has been measured. In addition, exploiting the complementary of CMOS technology, an anti-parallel diode pair with cut-off frequency of ~660 GHz consisting of an n-type and a p-type Schottky diode has been demonstrated in the same 130-nm CMOS process. Using the diodes, a frequency doubler and a tripler have been demonstrated. Additionally, the diodes have been utilized to implement 280-GHz and 860-GHz detectors for imaging. A fully-integrated 280-GHz 4×4 imager array exhibits measured NEP of 29pW/Hz^½ and responsivity of 5.1kV/W (323V/W without the amplifier). The 860-GHz detector without an amplifier achieves responsivity of 355V/W and NEP of 32pW/Hz^½. The NEP at 860GHz is 2X better than the best reported performance of MOSFET-based imagers without a silicon lens attached to the chip.