Temperature Dependence of the Impact Ionization Coefficients in AlAsSb Lattice Matched to InP

The temperature dependence of the ionization coefficients of AlAsSb has been determined from 210 K to 335 K by measuring the avalanche multiplication in a series of three
p⁺-i-n⁺
and two
n⁺-i-p⁺
diodes. Both electron and hole ionization coefficients reduce at approximately the same rate as the temperature increases but much less so than in InAlAs or InP. This results in a significantly smaller breakdown voltage variation with temperature of 13 mV/K in a 1.55 μm thick
p⁺-i-n⁺
structure and a calculated 15.58 mV/K for a 10 Gb/s InGaAs/AlAsSb separate absorption and multiplication avalanche photodiode (SAM-APD). Monte-Carlo modelling suggests that the primary reason for this reduced temperature dependence is the increased alloy scattering in the Sb containing alloy, reducing the impact of variation in phonon scattering rate with temperature.