Premium
Frequency‐Dependent Hopping Conductivity in a‐Si 1—y Ta y :H Thin Films
Author(s) -
Popescu B.,
Long A. R.
Publication year - 1998
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/(sici)1521-3951(199801)205:1<141::aid-pssb141>3.0.co;2-j
Subject(s) - variable range hopping , conductivity , condensed matter physics , impurity , electrical resistivity and conductivity , materials science , fermi level , analytical chemistry (journal) , physics , chemistry , chromatography , electron , quantum mechanics
Samples of a‐Si 1— y Ta y :H prepared by rf co‐sputtering with y ranging from 0 to 0.018 have been studied in sandwich configuration between room temperature and 20 K using dc and ac techniques. A sample with y = 0.009 shows variable range hopping in the dc and, as expected, the ac reduced conductivity scales well with reduced frequency. Values for the localisation length α —1 obtained from the ac data and from the dc low and high electric field dependencies are in good agreement. Samples with smaller y values, although they scale well, give unphysical localisation lengths. We account for this data provisionally in terms of the movement of the Fermi level from mid‐gap into states associated with Ta impurities.