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Impact ionization in AlxGa1-xASySb1-y avalanche photodiodes

Summary

Avalanche photodiodes (APDs) have been fabricated in order to determine the impact ionization coefficients of electrons (alpha) and holes (beta) in AlxGa1-xAsySb1-y lattice matched to GaSb for three alloy compositions: (x=0.40, y=0.035), (x=0.55, y=0.045), and (x=0.65, y=0.054). The impact ionization coefficients were calculated from photomultiplication measurements made on specially designed APDs, which allowed for both pure electron and pure hole injection in the same device. Photo-multiplication measurements were made at temperatures ranging from 77K to 300K for all three alloys. A quasi-physical model with an explicit temperature dependence was used to express the impact ionization coefficients as a function of electric-field strength and temperature. For all three alloys, it was found that alpha < beta at any given temperature. In addition, the values of the impact ionization coefficients were found to decrease as the aluminum concentration of the AlGaAsSb alloy was increased. A value between 1.2 and 4.0 was found for beta/x, which is dependent on temperature, alloy composition, and electric-field strength.
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Summary

Avalanche photodiodes (APDs) have been fabricated in order to determine the impact ionization coefficients of electrons (alpha) and holes (beta) in AlxGa1-xAsySb1-y lattice matched to GaSb for three alloy compositions: (x=0.40, y=0.035), (x=0.55, y=0.045), and (x=0.65, y=0.054). The impact ionization coefficients were calculated from photomultiplication measurements made on specially designed...

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Optimized growth of lattice-matched In(x)Al(1-x)N/GaN heterostructures by molecular beam epitaxy

Published in:
Appl. Phys. Lett., Vol. 90, No. 2, 8 January 2007, pp. 021922-1 - 021922-3.

Summary

The authors present a systematic study on the growth of the ternary compound In(x)Al(1-x)N by molecular beam epitaxy. This work concentrates on In mole fractions x around 0.17, as this composition is in-plane lattice matched to GaN. At a growth temperature of 540 degrees C, high quality material was obtained using a total metal to nitrogen flux ratio of ~1. Using these growth parameters, high quality GaN/InAlN superlattices were obtained without growth interruptions.
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Summary

The authors present a systematic study on the growth of the ternary compound In(x)Al(1-x)N by molecular beam epitaxy. This work concentrates on In mole fractions x around 0.17, as this composition is in-plane lattice matched to GaN. At a growth temperature of 540 degrees C, high quality material was obtained...

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