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Nature of electrical resistivity and structural stability in N‐doped GeTe models for reliable phase‐change materials
Author(s) -
Huang Bolong
Publication year - 2015
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.201451363
Subject(s) - materials science , amorphous solid , doping , electrical resistivity and conductivity , condensed matter physics , band gap , vacancy defect , amorphous semiconductors , phase change memory , phase (matter) , fermi level , valence (chemistry) , phase change , optoelectronics , nanotechnology , thin film , crystallography , engineering physics , chemistry , layer (electronics) , physics , electron , organic chemistry , quantum mechanics
We study the effects of nitrogen (N)‐doping on the electrical memory reliability of GeSbTe phase‐change materials based on GeTe prototype models. We find that the loss of secondary bonding (e.g., resonant interlayer bonding) determines the feasibility of various types of N‐doping that can be easily adopted by the GeSbTe system. We give a more generalized explanation beyond compliance with the formation of local Ge 3 N 4 motifs. The nitrogen‐induced change in local order produces crystalline GeTe with shallow states near the valence band edge. These states are localized on the nearest‐neighbor Ge sites, thus reducing the conductivity in the crystalline phase. This trend carries over to c‐GeTe with Ge vacancy. The N‐doped amorphous GeTe models exhibit enhanced degrees of band tail overlap, which pins the Fermi energy in the mid‐gap and thus gives rise to even higher resistivities in the amorphous phases.