Researchers build a silicon-graphene-germanium transistor
for future THz operation

In 1947, the first transistor, a bipolar junction
transistor (BJT), was invented in the Bell Laboratory and has since
led to the age of information technology. In recent decades, there
has been a persistent demand for higher frequency operation for a
BJT, leading to the inventions of new devices such as
heterojunction bipolar transistors (HBT) and hot electron
transistors (HET). The HBTs have enabled terahertz operations, but
their cut-off frequency is ultimately limited by the base transit
time; for the HETs, the demand of a thin base without pinholes and
with a low base resistance usually causes difficulties in material
selection and fabrication.