Electron tunneling in MIS capacitors with the MBE-grown fluoride layers on Si(1 1 1) and Ge(1 1 1): Role of transverse momentum conservation

The current–voltage characteristics of the metal–insulator–semiconductor tunneling structures with calcium fluoride are simulated using different theoretical models. The results are compared to the data of current measurements on the fabricated capacitors with 1–3 nm epitaxial fluorides. Best agreement is achieved imposing a condition of transverse momentum k⊥ conservation for a tunneling electron. This fact may be treated as an experimental proof for the k⊥ conservation in the examined high-quality structures which was not directly confirmed on more traditional structures with oxide dielectrics.

The current-voltage characteristics of the fabricated Au/fluoride/n-Si(1 1 1) capacitors are well reproduced by simulation using the correct model for tunneling probability (confirmation of a transverse electron momentum conservation in MIS tunneling).Figure optionsDownload as PowerPoint slideHighlights
► MIS structures with the 1–4 nm fluorides on n-Si(1 1 1) and n-Ge(1 1 1) are fabricated.
► Measured current-voltage curves are in an agreement to the refined simulation data.
► For Si(1 1 1), the large transverse electron momentum is conserved during tunneling.
► For Ge(1 1 1), the transverse momentum effect is small compared to the Si(1 1 1) case.