Authors: H.-E. Nilsson, E. Bellotti, K.F. Brennan, M. Hjelm

765

Authors: B.K. Ng, J.P.R. David, D.J. Massey, R.C. Tozer, G.J. Rees, Feng Yan, Jian H. Zhao, M. Weiner

1069

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.

1207

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.

451

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.

1081

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.

339

Authors: J.M. Albella, I. Montero, J.M. Martinez-Duart

527

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 *E*_{I }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 1×10^{8 }V/m in the 0.4-μm-thick a-Se HARP target was obtained as 1.87×10^{6 }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 *λ*_{E}/*λ* and the relaxation time ratio *τ*_{E}/*τ* saturate as the avalanche multiplication factor increases. In addition, the relaxation length ratio *λ*_{E}/*λ* and the relaxation time ratio *τ*_{E}/*τ* at 1×10^{8 }V/m were 2.75 and 14.66, respectively.

337

Authors: Martin Domeij, Bo Breitholtz, P. Liberski, A. Martinez, Peder Bergman

1327

Authors: A.X. Moronis, P.D. Bourkas, C.T. Dervos, C.A. Kagarakis

757