Abstract
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 <i>p<sup>+</sup>-i-n<sup>+</sup></i> and two <i>n<sup>+</sup>-i-p<sup>+</sup></i> 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 <i>p<sup>+</sup>-i-n<sup>+</sup></i> 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.
Highlights
A VALANCHE photodiodes (APDs) are widely used in optical detection systems as they can provide higher sensitivity and a larger signal to noise ratio than p-i-n diodes due to the internal gain that is provided by avalanche multiplication
Both add extra complexity and cost to the receiver modules unless the APD is made of a material which has a weak temperature dependent ionization process and small temperature coefficient of breakdown voltage, Cbd = ΔVbd/ΔT, where ΔVbd is the change in breakdown voltage and ΔT is the difference in temperature
We look at the avalanche multiplication characteristics in five AlAsSb p-i-n and two n-i-p structures that cover avalanche region widths of 80 nm to 1.55 μm over a temperature range of 210K to 335K
Summary
A VALANCHE photodiodes (APDs) are widely used in optical detection systems as they can provide higher sensitivity and a larger signal to noise ratio than p-i-n diodes due to the internal gain that is provided by avalanche multiplication This avalanche multiplication is a result of the impact ionization process that electrons and holes undergo at high electric fields, which can be highly temperature dependent. The temperature must be regulated by an embedded thermoelectric cooler (TEC) and temperature sensor for the purpose of temperature stabilization [5] Both add extra complexity and cost to the receiver modules unless the APD is made of a material which has a weak temperature dependent ionization process and small temperature coefficient of breakdown voltage, Cbd = ΔVbd/ΔT , where ΔVbd is the change in breakdown voltage and ΔT is the difference in temperature. As carriers undergoing impact ionization in a thicker avalanching structure will encounter more phonons than in a thinner structure, they will undergo a larger change in Vbd with temperature, so it is necessary to ensure that the widths of the high field regions are similar when comparing different material systems
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