Interface polarization model for a 2-dimensional electron gas at the BaSnO3/LaInO3 interface

Abstract

In order to explain the experimental sheet carrier density n2D at the interface of BaSnO3/LaInO3, we consider a model that is based on the presence of interface polarization in LaInO3 which extends over 2 pseudocubic unit cells from the interface and eventually disappears in the next 2 unit cells. Considering such interface polarization in calculations based on 1D Poisson-Schrödinger equations, we consistently explain the dependence of the sheet carrier density of BaSnO3/LaInO3 heterinterfaces on the thickness of the LaInO3 layer and the La doping of the BaSnO3 layer. Our model is supported by a quantitative analysis of atomic position obtained from high resolution transmission electron microscopy which evidences suppression of the octahedral tilt and a vertical lattice expansion in LaInO3 over 2–3 pseudocubic unit cells at the coherently strained interface.

The role of coherent epitaxy in forming a two-dimensional electron gas at LaIn1-xGaxO3/BaSnO3 interfaces

“…Considering the "interface polarization" in LIO can be correlated to the structural change caused by the orthorhombic/ cubic epitaxial strain in the case of LIO/BLSO interface, as reported previously 22 , σ s variation as a function of Ga alloying can also be viewed as variation in the epitaxial strain between the orthorhombic LIGO and the cubic BLSO layers. The epitaxial strain between LIO and BLSO is different from the usual biaxial strain that exist in the coherent epitaxial growth between two lattice-mismatched materials in other 2DEGs such as (AlGa)As/ GaAs 2,5,6 , (AlGa)N/GaN 3,9 , and (MgZn)O/ZnO 4,7,8 .…”

“…Although the 0.3% BLSO is not conducting, the slight doping is necessary to compensate for the large density deep acceptor states (5-6 × 10 19 cm −3 ) in BSO on STO substrates 22 . Lastly, the LIGO layer was deposited on the channel layer by using a stencil mask so as not to screen the entire contact area.…”

“…Recently, another perovskite polar/non-polar interface, LaInO 3 /BaSnO 3 (LIO/BSO), has been reported to have 2DEG [19][20][21][22][23] . It was proposed that the 2DEG formation may be related with the polar nature of LIO, since the interfaces of nonpolar BaHfO 3 or SrZrO 3 with La-doped BSO (BLSO) showed no conductance enhancement 20 , while the effect of oxygen vacancies and cation diffusion on the conductance of the interface have been tested and ruled out.…”

“…It was proposed that the 2DEG formation may be related with the polar nature of LIO, since the interfaces of nonpolar BaHfO 3 or SrZrO 3 with La-doped BSO (BLSO) showed no conductance enhancement 20 , while the effect of oxygen vacancies and cation diffusion on the conductance of the interface have been tested and ruled out. Subsequently, it has been suggested 22 that polarization in LIO near the interface with BSO induces 2DEG, based on the experimental data that showed the n 2D increases for the first 16 Å (~4 unit cells) of LIO, starts to decrease for thicker LIO, and then approaches to a constant value for thicker LIO beyond 100 Å (~25 unit cells). Such "interface polarization" model can explain, by using a large conduction band offset at the interface, the lack of the critical thickness of LIO for 2DEG formation.…”

Ab-Initio Study of Electronic and Structural Properties for BaSnO3 Compound Using DFT Calculations and FP-LAPW Technique in Wein2k Software

“…Equation 1.1 describes that sum of ionic radii is nearly equal to the bond length [13].Tolerance factor for the different structure is shown in table 1.3. piezoelectric devices (in which device produces AC voltage when we apply mechanical stress) etc [13]. perovskites that are used in highly effective photovoltaic are synthetic perovskites [15]. They are prepared same as solar cell by method of thin film [14].…”