Abstract
The hole multiplication factor in pnp In 0.52 Al 0.48 As/In 0.53 G 0.47 As single heterojunction bipolar transistors (HBT's) has been measured as a function of the base-collector bias. Hole impact ionization coefficient β p has been estimated by taking into account the Early effect, the collector-base leakage current I CBO , thermal effects and the spread in the nominal device processing parameters. Numerical corrections for dead space and current-induced collector charge density variations were made. The data obtained in this way agree with the most recent photomultiplication measurements available in literature.