Résumé
First order and low-frequency noise measurements are performed on GaInP/GaAs heterojunction bipolar transistors. The base current is decomposed into different components. Passivated transistors exhibit higher gain values, hence the passivation layer limits recombinations on the extrinsic device. Noise is measured in the 1 Hz-100 kHz frequency range on common-emitter-mounted transistors. The 1/f component is analyzed. The emitter series resistances are extracted. The proximity of the base contact on the smaller devices lead to a higher noise level due to enhanced recombinations. Extrinsic and intrinsic phenomena are put forward with the help of noise analysis versus base current and collector current density. An attempt is made to locate the 1/f noise sources. Unlike first order measurements, noise characterization shows that the passivation layer can be at the origin of recombination-type phenomena. (C) 1998 American Institute of Physics. [S0021-8979(98)04917-2].