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Electrical Contacts to p‐ZnSe Based on HgSe and ZnTe
Author(s) -
Einfeldt S.,
Behringer M.,
Nürnberger J.,
Heinke H.,
Behr T.,
Becker C. R.,
Hommel D.,
Landwehr G.
Publication year - 1995
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221870224
Subject(s) - ohmic contact , heterojunction , annealing (glass) , epitaxy , materials science , spinodal decomposition , molecular beam epitaxy , spinodal , condensed matter physics , optoelectronics , chemistry , phase (matter) , nanotechnology , metallurgy , physics , organic chemistry , layer (electronics)
Low resistance ohmic contacts to p‐ZnSe involving the use of HgSe are studied in detail. HgSe does not form an ohmic contact with p‐ZnSe because of a residual valence band offset at the heterojunction of 0.5 to 0.6 eV. Annealing of HgSe/ZnSe:N does not result in an ohmic contact because a large miscibility gap in Hg 1− x Zn x Se prevents a HgZn interdiffusion and therefore the formation of a graded heterojunction. The molecular beam epitaxial (MBE) growth of Hg 1− x Zn x Se does not circumvent this problem because these epitaxial layers suffer from a compositional phase separation due to spinodal demixing during MBE growth. A significant improvement of HgSe based contacts could be achieved by the use of ZnSe 1− x Te x :N transition layers between HgSe and ZnSe:N. Either by abrupt, graded, or multilayer heterojunctions, very low contact resistivities are obtained. The growth of ZnSe 1− x Te x :N layers on top of ZnSe:N is shown to reduce the carrier concentration in ZnSe:N by several orders of magnitude. A nitrogen diffusion process is believed to be responsible for this effect.