Impact Ionization Coefficients in (AlxGa1-x)0.52In0.48P and AlxGa1-xAs Lattice-Matched to GaAs

Abstract

The impact ionization characteristics of (AlxGa1-x)0.52In0.48P have been studied comprehensively across the full composition range. Electron and hole impact ionization coefficients (α and β, respectively) have been extracted from avalanche multiplication and excess noise data for seven different compositions and compared to those of AlxGa1-xAs. While both α and β initially decrease gradually with increasing bandgap, a sharp decrease in β occurs in (AlxGa1-x)0.52In0.48P when x > 0.61, while α decreases only slightly. α and β decrease minimally with further increases in x and the breakdown voltage saturates. This behavior is broadly similar to that seen in AlxGa1-xAs, suggesting that it may be related to the details of the conduction band structure as it becomes increasingly indirect in both alloy systems.