Impact Ionization Coefficients in (Al x Ga 1- x) 0.52 In 0.48 P and Al x Ga 1- x As Lattice-Matched to GaAs.

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 ($\alpha $ and $\beta $ , respectively) have been extracted from avalanche multiplication and excess noise data for seven different compositions and compared to those of AlxGa1-xAs. While both $\alpha $ and $\beta $ initially decrease gradually with increasing bandgap, a sharp decrease in $\beta $ occurs in (AlxGa1-x)0.52In0.48P when ${x} > 0.61$ , while $\alpha $ decreases only slightly. $\alpha $ and $\beta $ 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. [ABSTRACT FROM AUTHOR]