Abstract:Based on the first-principles method, the structural stability and the contribution of point defects such as O, Sr or Ti vacancies on two-dimensional electron gas of n- and p-type LaAlO$_{3}$/SrTiO$_{3}$ interfaces are investigated. The results show that O vacancies at p-type interfaces have much lower formation energies, and Sr or Ti vacancies at n-type interfaces are more stable than the ones at p-type interfaces under O-rich conditions. The calculated densities of states indicate that O vacancies act as donors and give a significant compensation to hole carriers, resulting in insulating behavior at p-type interfaces. In contrast, Sr or Ti vacancies tend to trap electrons and behave as acceptors. Sr vacancies are the most stable defects at high oxygen partial pressures, and the Sr vacancies rather than Ti vacancies are responsible for the insulator-metal transition of n-type interface. The calculated results can be helpful to understand the tuned electronic properties of LaAlO$_{3}$/SrTiO$_{3}$ heterointerfaces.
Gunkel F, Brinks P, Hoffmann-Eifert S, Dittmann R, Huijben M, Kleibeuker J E, Koster G, Rijnders G and Waser R 2012 Appl. Phys. Lett.100 052103
[8]
Herranz G, Basleti? M, Bibes M, Carrétéro C, Tafra E, Jacquet E, Bouzehouane K, Deranlot C, Hamzi? A, Broto J M, Barthélémy A and Fert A 2007 Phys. Rev. Lett.98 216803
[9]
Cantoni C, Gazquez J, Granozio F M, Oxley M P, Varela M, Lupini A R, Pennycook S J, Aruta C, Scotti di Uccio U, Perna P and Maccariello D 2012 Adv. Mater.24 3952
[10]
Gunkel F, Wicklein S, Hoffmann-Eifert S, Meuffels P, Brinks P and Huijben M 2015 Nanoscale7 1013
Hayward S A, Morrison F D, Redfern S A T, Salje E K H, Scott J F, Knight K S, Tarantino S, Glazer A M, Shuvaeva V and Daniel P 2005 Phys. Rev. B 72 054110