In-suit investigation of DC characteristics degradation in SiGe HBT included by halogen lamp irradiation

In present work, the direct current (DC) characteristics degradation of SiGe HBT under halogen lamp radiation were systematically investigated. Characteristics such as forward Gummel, reverse Gummel, junction leakage current, neutral base recombination and avalanche multiplication were measured in-suit and used to quantify the irradiation tolerance. A considerable increase in collector current and substrate current were found when the transistors were exposed to irradiation. The radiation-generated electron-hole pairs in space charge region of reversed collector-substrate junction are strongly responded. Because of the additional irradiation-induce excess carriers in neutral base region and space charge region of reversed base-collector junction, the neutral base recombination and avalanche multiplication increase for the irradiated transistors. The underlying physical mechanisms are analyzed and investigated in detail.