Measurements of the InGaAs Hole Impact Ionization Coefficient in InAlAs/InGaAs pnp HBTs

Abstract—The hole multiplication factor in pnp InAlAs/In- GaAs single heterojunction bipolar transistors (HBTs) has been measured as a function of the base-collector bias. The hole impact ionization coefficient p has been estimated taking into account the Early effect, ICBO, and thermal effects. Numerical corrections for dead space were made. The importance of considering second order effects is highlighted, showing that rough approximations can lead to an overestimation of the coefficient p. At low electric fields, the extracted coefficient agrees with the most recent photomultiplication measurements available in the literature. At high electric fields, hole impact ionization coefficient is estimated up to values previously not reported in the literature.