Investigation of 1/f Noise Mechanisms in Midwave Infrared HgCdTe Gated Photodiodes

Authors: Westerhout, R.J.; Musca, C.A.; Antoszewski, J.; Dell, J.M.; Faraone, L.

Source: Journal of Electronic Materials, Volume 36, Number 8, August 2007 , pp. 884-889(6)

Publisher: Springer

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Abstract:

In this work, gated midwave infrared (MWIR) Hg_1-xCd_x Te photodiodes are used to investigate the physical origin of 1/f noise generation. Gated photodiodes were fabricated on liquid-phase epitaxy p-type HgCdTe MWIR material with a vacancy-doped concentration of 1.6 × 10¹⁶ cm⁻³ and x = 0.31. CdTe was thermally deposited and used as both a passivant and a mask for the plasma-based type conversion, and ZnS was used as an insulator. Fabricated devices show a R ₀ A of 1-5 × 10⁴ Ωcm² with zero gate bias. Application of 2 V to the gate improves the R ₀ A by more than two orders of magnitude to 6.0 × 10⁶ Ωcm², which corresponds to the p-type surface being at transition between depletion and weak inversion. Trap-assisted tunneling (TAT) current was observed at negative gate biases and reverse junction biases. For gate biases greater than 3 V, a field-induced junction breakdown was observed. An I _n = α I ^β f ^−0.5 trend was observed above 200 pA reverse bias dark current, with α = 3.5 × 10⁻⁵ and β = 0.82, which corresponds to the TAT dominated region. Below 200 pA, junction generation-recombination (GR) current starts to dominate and this previously mentioned trend is no longer observed. Junction GR current was not seen to be correlated with 1/f noise in these photodiodes.

Keywords: 1/f noise; HgCdTe; midwave infrared (MWIR); gated photodiodes

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s11664-007-0120-x

Affiliations: 1: Email: ryan@ee.uwa.edu.au

Publication date: 2007-08-01