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.