Limits on Thinning of Boron Layers With/Without Metal Contacting in PureB Si (Photo)Diodes

A little more than a monolayer-thick pure-boron (PureB) layer was deposited on silicon at 250 °C by chemical vapor deposition (CVD), forming junctions with low saturation current. They displayed the same efficient suppression of electron injection as PureB diodes fabricated with a few nm-thick PureB layer deposited at 400 °C. Assuming high concentrations of acceptor states at the B-to-Si interface, induced by a fixed negative charge in the range from 5 × 10
¹³
cm
^-2
to 5 × 10
¹⁴
cm
^-2
, would be consistent with the experiments and device simulations that exhibit an efficient suppression of electron injection. Metallization of the B-layers was studied, showing that in many situations, thinning of the layer to monolayer thickness will lead to a significant increase in the electron injection.