Electron and hole impact ionization coefficients in InP determined by photomultiplication measurements

The electron and hole ionization coefficients α and β in (100) InP have been determined through analysis of photomultiplication data on p+‐n and n+‐p junctions grown by liquid phase epitaxy (LPE). A special device structure is described which allows reproducible thinning of the substrate in order to achieve pure carrier injection from either side of the p‐n junction. By fabricating wafers with depletion layer doping levels from 1.2×1015 to 1.2×1017 cm−3, α and β have been determined over a wider range of electric fields than previously reported. The ratio of β/α decreases from 4.0 to 1.3 as the electric field is increased from 2.4 to 7.7×105 V/cm.