Optimization and small-signal modeling of zero-bias InAs self-switching diode detectors. (February 2015)

• Record Type: Journal Article
• Authors: Westlund, A.; Sangaré, P.; Ducournau, G.; Iñiguez-de-la-Torre, I.; Nilsson, P.-Å.; Gaquière, C.; Desplanque, L.; Wallart, X.; Millithaler, J.F.; González, T.; Mateos, J.; Grahn, J.
• Is Part Of: Solid-state electronics. Volume 104(2015)
• Page Start: 79
• Page End: 85
• Publication Date: 2015-02
• Subjects: InAs -- Self-switching diode -- Millimeter-wave -- Terahertz -- Detector -- Small-signal modeling; Semiconductors -- Periodicals; Semiconducteurs -- Périodiques; 621.38152
• DOI: 10.1016/j.sse.2014.11.014
• Languages: English
• ISSNs: 0038-1101

Abstract

Highlights: A small-signal model for self-switching diodes (SSDs) as zero-bias direct detectors is proposed. Design dependence was confirmed by measurements on InAs SSDs. Cut-off frequency of the InAs SSDs calculated to 600 GHz. The InAs SSD detectors provided a linear response up to −3 dBm incident power. Abstract: Design optimization of the InAs self-switching diode (SSD) intended for direct zero-bias THz detection is presented. The SSD, which consists of nanometer-sized channels in parallel, was described using an equivalent small-signal circuit. Expressions for voltage responsivity and noise equivalent power (NEP) were derived in terms of geometrical design parameters of the SSD, i . e . the channel length and the number of channels. Modeled design dependencies were confirmed by RF and DC measurements on InAs SSDs. In terms of NEP, an optimum number of channels were found with the detector driven by a 50 Ω source. With a matched source, the model predicted a responsivity of 1900 V/W and NEP of 7.7 pW/Hz ½ for a single-channel InAs SSD with 35 nm channel width. Monte Carlo device simulations supported observed design dependencies. The proposed small-signal model can be used to optimize SSDs of any material system for low-noise and high-frequency operation as zero-bias detectors. In large signal measurements, the responsivity of the InAs SSDs exhibited a 1 dB deviation from linear responsivity at an input power of −3 dBm from a 50 Ω source.