Reduction of NEP variations for terahertz detectors using Schottky barrier diodes in CMOS

Abstract

Variations of low-frequency noise including flicker and Lorentzian spectra are the dominant source of variation of noise equivalent power (NEP) for terahertz detectors using diode-connected N-type MOS (NMOS) transistors. The low-frequency noise of Schottky diodes fabricated in the same CMOS process as the NMOS detectors are dominated by generation and recombination noise. At 1 MHz modulation frequency, the noise of Schottky barrier diodes (SBDs) and its variation are ∼2× lower than those of diode-connected NMOS transistors. It should be possible to reduce the variation of NEP by ∼2× using Schottky diode detectors modulated at 1 MHz.