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Temperature‐Dependent Electronic Transport in Non‐Bulk‐Resistance‐Variation Nitrogen‐Doped Cr 2 Ge 2 Te 6 Phase‐Change Material
Author(s) -
Shuang Yi,
Hatayama Shogo,
Ando Daisuke,
Sutou Yuji
Publication year - 2021
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.202000415
Subject(s) - amorphous solid , materials science , thermal conduction , thermionic emission , electrical resistivity and conductivity , variable range hopping , condensed matter physics , atmospheric temperature range , tungsten , doping , phase (matter) , electron , chemistry , crystallography , optoelectronics , electrical engineering , thermodynamics , composite material , metallurgy , physics , quantum mechanics , engineering , organic chemistry
The electronic transport mechanism of the nitrogen‐doped Cr 2 Ge 2 Te 6 (NCrGT) phase‐change material (PCM) is studied, showing almost zero resistivity variation upon phase transition. A similar low‐temperature variable‐range hopping (VRH) behavior in both the amorphous and crystalline phases of the NCrGT PCM is observed by measuring the temperature‐dependent resistivity. At high temperatures above 300 K, the conduction mechanism in the amorphous NCrGT is thermally activated band conduction, while the carrier transport in the crystalline NCrGT is still driven by VRH. Moreover, Hall property measurements reveal a thermally activated carrier in the amorphous NCrGT and mobility‐driven hopping conduction in the crystalline NCrGT at a high temperature range from 300 to 400 K. The conduction mechanism difference between the amorphous and crystalline NCrGT/tungsten (W) contacts is further investigated by measuring the temperature‐dependent I – V characteristics. The conduction in the amorphous NCrGT/W contact is dominated by thermionic‐field emission, while the transport mechanism through the crystalline NCrGT/W interface is controlled by the defect‐assisted tunneling current. Such noticeable conduction mechanism variation results in a large contact resistance contrast in a memory cell.