Tuning the electronic properties of LaAlO 3 /SrTiO 3 interfaces by irradiating the LaAlO 3 surface with low-energy cluster ion beams
Tuning the electronic properties of LaAlO 3 /SrTiO 3 interfaces by irradiating the LaAlO 3 surface with low-energy cluster ion beams
复制标题
DOI：
10.1103/physrevb.97.035146
复制
发表时间：
2017-04
影响因子：
3.7
通讯作者：
K. Ridier;D. Aureau;Bruno B'erini;Y. Dumont;N. Keller;J. Vigneron;A. Etcheberry;A. Fouchet
中科院分区：
文献类型：
--
作者：
K. Ridier;D. Aureau;Bruno B'erini;Y. Dumont;N. Keller;J. Vigneron;A. Etcheberry;A. Fouchet
采用X射线光电子能谱（XPS）和电输运测量相结合的方法，研究了低能氩离子束辐照对LaAlO 3/SrTiO 3（LAO/STO）异质界面化学和电子性质的影响.由于其独特的特征，我们证明LAO表面的短时间簇离子照射会导致掩埋STO衬底的化学性质发生显着变化，其中（1）Ti原子氧化态的降低（从Ti 4+到Ti 3+和Ti 2+）与LAO表面氧空位的形成相关，以及（2）Sr原子产生新的表面态。与通过使用较高能量离子束技术通常观察到的相反，这导致LAO/STO界面处的电导率增加。我们的XPS数据清楚地揭示了钛和锶原子上的动力学过程的存在，这与团簇离子束辐照的效果竞争。这些弛豫效应部分归因于离子诱导的氧空位在整个异质结构中的扩散，因为也证明了远离辐照区域的界面金属性的增加。本文强调了通过表面工程调节LAO/STO界面电性能的可能性，实验证实了LAO化学与LAO/STO界面电性能之间的密切联系。
We have investigated the effects of low-energy ion beam irradiations using argon clusters on the chemical and electronic properties of LaAlO3/SrTiO3 (LAO/STO) heterointerfaces by combining x-ray photoelectron spectroscopy (XPS) and electrical transport measurements. Due to its unique features, we demonstrate that a short-time cluster ion irradiation of the LAO surface induces significant modifications in the chemical properties of the buried STO substrate with (1) a lowering of Ti atoms oxidation states (from Ti4+ to Ti3+ and Ti2+) correlated to the formation of oxygen vacancies at the LAO surface and (2) the creation of new surface states for Sr atoms. Contrary to what is generally observed by using higher energy ion beam techniques, this leads to an increase of the electrical conductivity at the LAO/STO interface. Our XPS data clearly reveal the existence of dynamical processes on the titanium and strontium atoms, which compete with the effect of the cluster ion beam irradiation. These relaxation effects are in part attributed to the diffusion of the ion-induced oxygen vacancies in the entire heterostructure since an increase of the interfacial metallicity is also evidenced far from the irradiated area. This paper highlights the possibility of tuning the electrical properties of LAO/STO interfaces by surface engineering, confirming experimentally the intimate connection between LAO chemistry and electronic properties of LAO/STO interfaces.