Strain relaxation of epitaxial (Ba0.6Sr0.4)(Zr0.3Ti0.7)O3 thin films grown on SrTiO3 substrates by pulsed laser deposition

Abstract

High crystalline quality (Ba0.6Sr0.4)(Zr0.3Ti0.7)O3 (BSTZ) thin films were epitaxially grown by pulsed laser deposition on (001) SrTiO3 single crystal substrates. Their epitaxial nature was revealed by x-ray and electron diffraction. Thinnest film (∼9 nm) has largest out-of-plane lattice constant (4.135 Å) and tetragonality (1.06). Films are under compressive strain. Film thicknesses above ∼9 nm were started to relax as revealed from reciprocal space mapping. Thicknesses deduced from x-ray diffraction and transmission electron microscopy methods are in good agreement. Critical thickness to relieve strain of the BSTZ film is about 7.6±0.4 nm.

Antiferromagnetic Oxide Thin Films for Spintronic Applications

“…In this work, we deposited Cr 2 O 3 and α-Fe 2 O 3 by using radio frequency (RF) magnetron sputtering at high temperature from 2 Cr and Fe sputtering targets, respectively, on (11)(12)(13)(14)(15)(16)(17)(18)(19)(20) Al 2 O 3 (A-plane sapphire) substrates in the presence of both oxygen and argon. Initially, we varied the oxygen flow rate from 1.0 to 5.0 sccm while keeping the argon flow rate at 70 sccm and the chamber pressure at 3 mTorr.…”

“…After the deposition, the films were annealed at 700 • C for one hour at 2 mTorr in the presence of oxygen at 1 mTorr. XRD θ-2θ patterns of film in Figure 1a show the peak at 2θ = 36.02 • , which comes from the Cr 2 O 3 [11][12][13][14][15][16][17][18][19][20] Bragg reflection corresponding to the corundum structure. The peak at 37.8 • is the [11][12][13][14][15][16][17][18][19][20] Al 2 O 3 substrate peak.…”

“…XRD θ-2θ patterns of film in Figure 1a show the peak at 2θ = 36.02 • , which comes from the Cr 2 O 3 [11][12][13][14][15][16][17][18][19][20] Bragg reflection corresponding to the corundum structure. The peak at 37.8 • is the [11][12][13][14][15][16][17][18][19][20] Al 2 O 3 substrate peak. The films grown at oxygen flow varying from 2.0 to 3.5 sccm show similar structure with different strains in the films as discussed in detail below.…”

“…Figure 1b shows the rocking curve data for the [11][12][13][14][15][16][17][18][19][20] Bragg reflection of the same 20-nm Cr 2 O 3 sample. The full width at half maximum value of the rocking curve is 0.145 • .…”

“…However, the film deposited with 3.5 sccm pressure shows a much broader XRD peak. The broadening may result from the shorter out of plane coherence length in thinner film [19]. Thus, for the subsequent depositions, we choose the oxygen flow of 2.5 sccm for all the deposition conditions as this flow of oxygen provides the optimum oxidation for both oxides.…”