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Temperature‐dependent electrical transport mechanism in amorphous Ge 2 Sb 2 Te 5 films
Author(s) -
Wu H. Y.,
Wang W.,
Lu W. J.
Publication year - 2016
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.201600045
Subject(s) - amorphous solid , materials science , electrical resistivity and conductivity , variable range hopping , condensed matter physics , conductance , density of states , quantum tunnelling , activation energy , atmospheric temperature range , fermi level , biasing , optoelectronics , thermal conduction , voltage , crystallography , electrical engineering , chemistry , composite material , thermodynamics , physics , quantum mechanics , engineering , organic chemistry , electron
We study the electrical transport mechanism of amorphous Ge2 Sb2 Te5 (GST) phase‐change memory material. Amorphous GST films with 10–100 nm thicknesses were fabricated in trilayer geometry by using metal top and bottom electrodes. The temperature and voltage bias dependences of the electrical conductance were measured and analyzed using different models. Thermally activated conductance was observed at high temperatures. The estimated activation energy E a and carrier density n were 0.36–0.45 eV and ∼ 10 18 cm −3 , respectively. With a decrease in temperature, variable‐range‐hopping (VRH) conductivity was induced in moderate temperature range (150–250 K), which was associated with the diffusive regime. At low temperatures ( T < 50 K ), electrical transport occurred predominantly by inelastic hopping through directed chains of localized states. The localized electronic states of amorphous GST were observed experimentally by our tunneling density‐of‐states (DOS) measurements.