Nanolayer boron-semiconductor interfaces and their device applications

Nanolayers of pure boron (PureB) deposited on Si form p + -type regions at deposition temperatures from 50 • C to 700 • C. At 700 • C, commercial PureB photodiodes are produced for advanced detection systems including those in extreme-ultraviolet (EUV) lithography systems.In addition, potent MEMS applications of B-nanolayers have been demonstrated.Attractive diode characteristics were also found for devices where Ga wetting-layers were applied to the Si surface, both with/without an additional B capping-layer.The resulting "PureGa" and "Pure-GaB" diodes are assessed here in the light of investigations focused on the B-Si interface properties in PureB diodes.A very high density of acceptor states at the Si interface appears to be related to the p-dopant property of both B and Ga, even though diffusion into the Si is not expected for the applied processing temperatures from 50 • C to ~ 450 • C.