Determination of impact ionization coefficients in InP by analysis of photomultiplication and noise measurements

The electron and hole impact ionization coefficients, α and β, respectively have been determined in InP using specially fabricated devices that permit both pure electron and pure hole injection. Ionization coefficients calculated from photocurrent multiplication data for devices with three different active region doping levels indicate a ratio of β/α which decreases from 4.0 to 1.3 for fields of 2.4 to 7.7 × 10⁵V/cm, respectively. Avalanche noise measurements have been performed on the same devices and the results indicate a value of β/α that is generally consistent with the photocurrent multiplication results.