Determination of the excess noise of avalanche photodiodes integrated in 0.35-μm CMOS technologies

Hole initiated avalanche multiplication characteristics of 4H-SiC avalanche photodiodes have been studied. The diodes had n+-n-p SiC epitaxial layers grown on a p-type substrate. These 1 mm2 devices had very low dark currents and exhibited sharp breakdown at voltages of approximately 500V. The diodes multiplication characteristics appeared to be identical when the wavelength of the illuminating light from the top varied from 288 to 325nm, implying that almost pure hole initiated multiplication was occurring. The multiplication factor data were modelled using a local multiplication model with impact ionization coefficients of 4H-SiC reported by various authors. The impact ionization coefficients extracted from submicron devices by Ng et al. were found to give accurate predictions for multiplication factors within the uncertainties of the doping levels. This result suggests that their ionization coefficients can be applied to thicker bulk 4H-SiC structures.

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Generalized excess noise factor for avalanche photodiodes of arbitrary structure

IEEE Transactions on Electron Devices ◽

10.1109/16.47763 ◽

1990 ◽

Vol 37 (3) ◽

pp. 599-610 ◽

Cited By ~ 22

Author(s):

N.Z. Hakim ◽

B.E.A. Saleh ◽

M.C. Teich

Keyword(s):

Avalanche Photodiodes ◽

Noise Factor ◽

Excess Noise ◽

Excess Noise Factor ◽

Arbitrary Structure

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Characterisation of Low Noise 4H-SiC Avalanche Photodiodes

Materials Science Forum ◽

10.4028/www.scientific.net/msf.645-648.1081 ◽

2010 ◽

Vol 645-648 ◽

pp. 1081-1084

Author(s):

James E. Green ◽

W.S. Loh ◽

J.P.R. David ◽

R.C. Tozer ◽

Stanislav I. Soloviev ◽

...

Keyword(s):

Silicon Carbide ◽

Avalanche Photodiodes ◽

Depletion Region ◽

Low Noise ◽

Excess Noise ◽

Local Model ◽

Prior Work ◽

Absorption Layer ◽

Impact Ionisation ◽

Dark Currents

We report photomultiplication, M, and excess noise, F, measurements at 244nm and 325nm in two 4H-SiC separate absorption and multiplication region avalanche photodiodes (SAM-APDs). Sample A is a 4 x 4 array of 16 SAM-APDs. This structure possesses a relatively thin absorption layer resulting in more mixed injection, and consequently higher noise than sample B. The absorption layer of sample B does not deplete, so 244nm light results in >99% absorption outside the depletion region resulting in very low excess noise. Both structures exhibit very low dark currents and abrupt uniform breakdown at 194V and 624V for samples A and B respectively. Excess noise is treated using a local model [1]. The effective ratio of impact ionisation coefficients (keff) is approximately 0.007, this indicates a significant reduction in the electron impact ionisation coefficient, α, compared to prior work [2-5]. We conclude that the value of α will require modification if thick silicon carbide structures are to fit the local model for multiplication and excess noise.

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