Papers by Keyword: Impact Ionization

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Authors: H.-E. Nilsson, E. Bellotti, K.F. Brennan, M. Hjelm
Authors: B.K. Ng, J.P.R. David, D.J. Massey, R.C. Tozer, G.J. Rees, Feng Yan, Jian Hui Zhao, M. Weiner
Authors: W.S. Loh, J.P.R. David, Stanislav I. Soloviev, H.Y. Cha, Peter M. Sandvik, J.S. Ng, C. Mark Johnson
Abstract: The hole dominated avalanche multiplication characteristics of 4H-SiC Separate Absorption and Multiplication avalanche photodiodes (SAM-APDs) were determined experimentally and modeled using a local multiplication model. The 0.5x 0.5mm2 diodes had very low dark current and exhibited sharp, uniform breakdown at about 580V. The data agree with modeling result using extrapolated impact ionization coefficients reported by Ng et al. and is probably valid for electric fields as low as ~0.9MV/cm at room temperature provided that both the C-V measurements and electric field determination in this work are correct. The packaged devices demonstrate a positive temperature coefficient of breakdown voltage for temperatures ranging from 100K to 300K which is a desired feature for extreme environment applications.
Authors: Hamid Fardi, Bart van Zeghbroeck
Abstract: Modeling and simulation of 3C-SiC power devices such as MOSFETs and diodes requires a model for the breakdown field that is consistent with the Monte-Carlo-simulated ionization rates of electron and holes and supported by experimental results. The challenge one faces is the limited number of publications reporting such calculations and the limited availability of high-quality ionization breakdown data for 3C-SiC diodes. We therefore performed a series of 2D simulations of both n-type and p-type Schottky diodes and p+-n diodes that confirms the general breakdown field trend with doping density obtained from experiments. We uncovered a difference between n-type and p-type diode breakdown behavior, identified the discrepancy between the calculations and the experimental data, and extracted a simple breakdown field model, useful for further 3C-SiC device design and simulation.
Authors: Vladimir Ilich Sankin, Nikita S. Averkiev, Andrey M. Monakhov, Pavel P. Shkrebiy, Alla A. Lepneva, Andrey G. Ostroumov, Pavel L. Abramov, Elena V. Bogdanova, Sergey P. Lebedev, Anatoliy M. Strelchuk
Abstract: In this work, we have studied I-V characteristics of Al breakdown in 6H-, 4H- and 15R-SiC in electrical field. As a result there obtained the next original data: 1) decreasing dependence of breakdown field due to the concentration increase in the range of Na – Nd = 5x1017–1019 cm-3; 2) absence of low temperature breakdown when Na - Nd< 1017 cm-3; 3) increasing of breakdown field while temperature declines from 77K to 4.2K; 4) at 300K the breakdown field decreases and the breakdown takes place in samples with the absence of low temperature breakdown; 5) gigantic enhancement of breakdown field at F||C. 6) the theoretical analysis based on the theory of a zero radius potential supports the probability of breakdown field enhancement at F||C.
Authors: James E. Green, W.S. Loh, J.P.R. David, R.C. Tozer, Stanislav I. Soloviev, Peter M. Sandvik
Abstract: 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.
Authors: W.S. Loh, C. Mark Johnson, J.S. Ng, Peter M. Sandvik, Steve Arthur, Stanislav I. Soloviev, J.P.R. David
Abstract: 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.
Authors: J.M. Albella, I. Montero, J.M. Martinez-Duart
Authors: Wug Dong Park, Kenkichi Tanioka
Abstract: Avalanche multiplication of the 0.4-μm-thick a-Se HARP (High-gain Avalanche Rushing amorphous Photoconductor) target was obtained at a high electric field. To study the drift velocity of hot carriers in the a-Se layer, the energy-and field-dependent energy relaxation length was considered in the lucky-drift model. The impact ionization energy EI of 2.0 eV and the optical phonon energy ћω of 31 meV for a-Se were used to obtain the impact ionization parameters in the a-Se layer. The drift velocity of hot carriers at 1×108 V/m in the 0.4-μm-thick a-Se HARP target was obtained as 1.87×106 cm/s. The drift velocity of hot carriers saturates as the electric field and the avalanche multiplication factor increase. In the 0.4-μm-thick a-Se HARP target, the relaxation length ratio λE/λ and the relaxation time ratio τE/τ saturate as the avalanche multiplication factor increases. In addition, the relaxation length ratio λE/λ and the relaxation time ratio τE/τ at 1×108 V/m were 2.75 and 14.66, respectively.
Authors: Martin Domeij, Bo Breitholtz, P. Liberski, A. Martinez, Peder Bergman
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