Local structure and electrical switching in Al20Te75X5 (X = Si, Ge, As, Sb) glasses

• DOI: 10.1007/s00339-020-03471-z
• Publication Date: 2020-03-21T11:02:40Z
• Authors: P. T. Wilson; R. Ramanna; Shweta Chahal; Roopali Shekhawat; M. Madesh Kumar; K. Ramesh
• Keywords: Coordination number; Lone pair; Rigidity (electromagnetism)

Al20Te75X5 (X = Si, Ge, As, Sb) glasses prepared by the melt quenching method exhibit threshold switching. Local structure of these glasses studied by 27Al MAS-NMR measurements reveals that Al is in four-, five- and sixfold coordination. For Al to be in higher coordination states, Te transfers its lone pair electrons. Due to the higher coordinated Al and Te, the cross-linking in the network increases. The increased cross-linking and rigidity constraint the structural reorganization required for memory switching, resulting in the observed threshold switching. Interestingly, glass transition and crystallization temperatures were found to be high for Al20Te75Si5 glass and low for Al20Te75Sb5 glass. Also, the bond energy of Si–Te is higher than the bond energy of Sb–Te. Correspondingly, the threshold voltage is high for Al20Te75Si5 glass and low for Al20Te75Sb5 glass. The [6]Al site peak shows a split which may offer greater insight into the structure of these glasses.