https://doi.org/10.1140/epjb/e2003-00103-x
Location of the minimum of the differential tunneling resistance R(V) in a superconductor-degenerate semiconductor Schottky contact
1
Istituto di Cibernetica del Consiglio Nazionale delle Ricerche “E. Caianiello”, Pozzuoli (Napoli), Italy
2
INFM - Coherentia - Dipartimento di Scienze Fisiche Università Federico II, Napoli, Italy
3
Institute of Radio Engineering and Electronics
of the Russian Academy of Sciences, Moscow, Russia
4
INFM-Dipartimento di Scienze Fisiche Università di Salerno,
Salerno, Italy
Corresponding author: a c.nappi@cib.na.cnr.it
Received:
11
November
2002
Revised:
21
February
2003
Published online:
11
April
2003
Measurements of differential resistance in a superconductor-degenerate
semiconductor junction 
at T=1.6 K show close similarity
to those for a conventional superconductor-insulator- normal metal junction,
except for the position of the minimum which is located at 3.6 meV. Using
a simple model for the charge screening at the Schottky barrier, we give an
argument why this minimum is by far displaced with respect to the
superconducting gap energy (
meV for bulk Nb). We argue
that a rebuilding of the density of states takes place at the barrier, due
to the imperfect metal screening in the degenerate semiconductor. Energy
states close to the degenerate semiconductor Fermi energy are depleted at
the barrier and are not available for tunneling, up to an energy Eg which
adds to the superconducting gap 
.
PACS: 73.30.+y – Surface double layers, Schottky barriers, and work functions / 73.40.-c – Electronic transport in interface structures / 74.80.Fp – Point contacts; SN and SNS junctions
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2003
