Monolayer Be δ-doped heterostructure bipolar transistor fabricated using doping selective base contact

Abstract

A heterostructure bipolar transistor (HBT) with a base δ-doping of 6×1014cm−2, near the physical limit of one monolayer (ML) is reported. The devices exhibits a current gain of 15. The doping confinement of the δ layer is 15 Å. To fabricate the HBT without inducing dopant diffusion or using sensitive etching, a new low-temperature basecontacting procedure (Tmax = 420°C) which requires no base-emitter etching has been development. This has the additional benefits of greatly reducing surface recombination and yielding a planar structure.