Abstract

The impact of the material quality on the reliability of heterojunction bipolar transistors (HBT) is discussed. So far, a clear impact of the material structure is clearly found on the electrical performances of HBT's. The InGaP/GaAs heterostructure shows impressive reliability figure compared to the AlGaAs/GaAs ones. This behavior is strongly related to the surface passivation of the extrinsic base layer. Three main behaviors are believed to have a positive impact on the reliability: higher electron injection, better stability of the InGaP material, better InGaP passivation. Aging tests have been carried out for more than 6,500hr on 100 devices without any catastrophic failure at stress as high as junction temperature of 200°C and collector current of 40kA cm-2. This result confirms the excellent reliability of InGaP/GaAs HBT and enables to use them in high power applications.