Impact of defect occupation on conduction in amorphous Ge2Sb2Te5

• Published in: Scientific reports Vol. 6; no. 1; p. 31699
• Main Authors: Kaes, Matthias, Salinga, Martin
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16.08.2016; Nature Publishing Group
• Subjects: 639/301/1005/1008; 639/766/119/995; Conduction; Crystallization; Defects; Electric fields; Humanities and Social Sciences; Illumination; multidisciplinary; Science; Spectrum analysis; Temperature effects
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep31699

Storage concepts employing the resistance of phase-change memory (PRAM) have matured in recent years. Attempts to model the conduction in the amorphous state of phase-change materials dominating the resistance of PRAM devices commonly invoke a connection to the electronic density-of-states (DoS) of the active material in form of a “distance between trap states s ”. Here, we point out that s depends on the occupation of defects and hence on temperature. To verify this, we numerically study how the occupation in the DoS of Ge 2 Sb 2 Te 5 is affected by changes of temperature and illumination. Employing a charge-transport model based on the Poole-Frenkel effect, we correlate these changes to the field- and temperature-dependent current-voltage characteristics of lateral devices of amorphous Ge 2 Sb 2 Te 5 , measured in darkness and under illumination. In agreement with our calculations, we find a pronounced temperature-dependence of s . As the device-current depends exponentially on the value of s , accounting for its temperature-dependence has profound impact on device modeling.