Combinatorial Material Science and Strain Engineering Enabled by Pulsed Laser Deposition Using Radially Segmented Targets

Abstract

Vertical composition gradients of ternary alloy thin films find applications in numerous device structures. Up to now such gradients along the growth direction have not been realized by standard pulsed laser deposition (PLD) systems. In this study, we propose an approach based on a single elliptically segmented PLD target suited for the epitaxial growth of vertically graded layers. The composition of the thin films can be varied by a simple adjustment of the position of the PLD laser spot on the target surface. We demonstrate this principle for the Mg x Zn1–x O alloy system. Such vertically composition-graded Mg x Zn1–x O thin films exhibit high optical quality and a well-defined Mg-content for each layer. No signs of interdiffusion of Mg-atoms between the layers have been found. Further, this method is capable to deposit homogeneous thin films with any desired, well-defined cation composition having the same high optical and structural quality as films grown by conventional PLD.

Data‐Driven Materials Science: Status, Challenges, and Perspectives

“…Since then, multiple improved materials synthesis and characterization techniques have been introduced. [171][172][173][174][175] They have enabled the rapid generation of composition-structure-property relationships. [176][177][178][179][180] State-of-the-art deposition techniques, such as combinatorial laser-molecular beam epitaxy (CLMBE) [173] introduced around the year 2000, can be used to create temperature and composition gradients across the sample and provide control of the deposition in three dimensions.…”

“…In 1965, the first composition gradients could be achieved in thin‐film material codeposition, offering a more efficient replacement for the one‐by‐one creation and study of materials. Since then, multiple improved materials synthesis and characterization techniques have been introduced . They have enabled the rapid generation of composition–structure–property relationships .…”

Band Offsets at κ-([Al,In]xGa1–x)2O3/MgO Interfaces

“…The variation and control of the alloy composition is accomplished by the respective fixed radial position r of the PLD laser spot on the employed elliptically-segmented target. A detailed description of this technique can be found in Reference 45 . The targets were either homogeneous Ga2O3 + 1 wt.% SnO2 or MgO targets for the κ-Ga2O3 template layer or the MgO dielectric layer, respectively.…”

“…The elliptically-segmented target for the κ-(InxGa1-x)2O3 alloy layers was a (In0.4Ga0.6)2O3/Ga2O3 target with additional 1.5 at.% SnO2 in each segment and for the κ-(AlxGa1-x)2O3 alloy layers a (Al0.4Ga0.6)2O3/Ga2O3 or a (Al0.2Ga0.6)2O3/Ga2O3 target with additional 2 at.% SnO2 in each segment for both targets was employed, respectively. The exact target geometries can be found in References 24,25,45 . The presence of tin is necessary to facilitate the growth of the Ga2O3 based layers in the metastable orthorhombic modification for the PLD deposition method [18][19][20]23 .…”

Monolithic Forward‐Looking Photodetector for Use as Ultra‐Compact Wavemeter with Wide Spectral Range

“…This can be achieved by intentional variation of the fluxes/partial pressures during growth in molecular beam epitaxy (MBE) or the variation of precursor fluxes in metal‐organic vapor phase epitaxy (MOVPE). For MBE and MOVPE (unintentional) vertical composition gradients have been reported for (Mg,Zn)O due to the “composition‐pulling effect.” Also for pulsed laser deposition, a scheme has been developed to fabricate vertically composition graded layers using radially segmented targets …”