Numerical simulation of impact ionization in Ge/AlxGa1-xAs avalanche photodiode

Impact ionization in Ge/AlxGa1-xAs p-i-n heterostructures has been studied using the Monte Carlo technique. The thin (< 300 nm) Ge/AlxGa1-xAs single heterojunction structure was found to exhibit large hole (beta) to electron (alpha) ionization coefficient ratio, owing to a higher beta in the Ge layer and a lower alpha in the AlxGa1-xAs layer, together with the dead space effects. The Ge/AlxGa1-xAs avalanche photodiodes are attractive for applications where a wide wavelength detection range is required for compatibility with multiple sources such as in the emerging active optical cable and optical interconnect applications, as well as in the established optical fiber telecommunication systems.(C) 2010 American Institute of Physics. [doi: 10.1063/1.3480407]