Temperature dependent minority electron mobilities in strained si_1-xge_x (0. 2 < × < 0. 4) layers

Temperature-dependent minority electron mobilities in p-type SiGe have been measured for the first time. Measurements were made on test npn SiGe/Si heterojunction bipolar transistors (HBT's) with pseudomorphic p-type Sii-a-Ge (0. 2 < x < 0. 4) base layers. Magnetotransport measurements were performed on the fabricated HBT's to obtain the minority electron mobilities in the heavily B-doped base layers for temperatures ranging from 5 to 300 K. The measured minority electron mobilities exhibited sharp increase with decreasing temperature, and also showed enhancement with decreasing base Ge composition. The cut-off frequency technique was also employed to estimate the room temperature minority electron mobilities of the alloys and the results confirmed the trend in mobilities with Ge composition as determined by the magnetotransport technique. Heterojunction bipolar transistor, minority carrier mobility, SiGe alloy.