Lattice Mismatch Stress Research Articles

Strong spin-lattice entanglement in cobaltites

Strongly correlated electronic system contains strong coupling among multi-order parameters and is easy to efficiently tune by external field. Cobaltite (LaCoO<sub>3</sub>) is a typical multiferroic (ferroelastic and ferromagnetic) material, which has been extensively investigated over decades. Conventional research on cobaltites has focused on the ferroelastic phase transition and structure modulation under stress. Recently, researchers have discovered that cobaltite thin films undergo a paramagnetic-to-ferromagnetic phase transition under tensile strain, however, its origin has been controversial over decades. Some experimental evidence shows that stress leads the valence state of cobalt ions to decrease, and thus producing spin state transition. Other researchers believe that the stress-induced nano-domain structure will present a long-range ordered arrangement of high spin states, which is the main reason for producing the ferromagnetism of cobalt oxide films. In this paper, we review a series of recent researches of the strong correlation between spin and lattice degrees of freedom in cobalt oxide thin films and heterojunctions. The reversible spin state transition in cobalt oxide film is induced by structural factors such as thin-film thickness, lattice mismatch stress, crystal symmetry, surface morphology, interfacial oxygen ion coordination, and oxygen octahedral tilting while the valence state of cobalt ions is kept unchanged, and thus forming highly adjustable macroscopic magnetism. Furthermore, the atomic-level precision controllable film growth technology is utilized to construct single cell layer cobaltite superlattices, thereby achieving ultra-thin two-dimensional magnetic oxide materials through efficient structure regulation. These advances not only clarified the strong coupling between lattice and spin order parameters in the strongly correlated electronic system, but also provided excellent candidate for the realization of ultra-thin room temperature ferromagnets that are required by oxide spintronic devices.

Stress Analysis of Flexible GaInP/GaAs/InGaAs Solar Cells Based on Cu Thin‐Film Substrates

The stress of GaInP/GaAs/InGaAs triple‐junction (3J) solar cells with different thicknesses of Cu thin‐film substrates is analyzed. X‐ray diffractometer and metallographic examination show that the unstable as‐deposited Cu film undergoes room‐temperature self‐annealing, which results in grain growth and changes the internal stress of the Cu film over time. A suitable Cu thickness (18 μm) for 3J solar cells is obtained, whose internal stress can offset the stress caused by the epitaxial mismatch. The flexible 3J solar cell with 18 μm Cu film has the lowest curvature of 8.24 m−1 under the combined effect of thermal stress and lattice mismatch stress. The photovoltaic conversion efficiency reaches 35.02% with the open‐circuit voltage of 3.03 V under AM1.5G spectrum. Cu films with a thickness of 14–28 μm have little effect on the optoelectronic properties of the final device. Reducing the curvature of lattice‐mismatched GaInP/GaAs/InGaAs solar cell devices is beneficial for realizing large‐scale flexible solar cell modules.

Effects of anisotropic surface drift diffusion on the strained heteroepitaxial nanoislands subjected to electromigration stressing

A systematic study based on self-consistent dynamical simulations is presented for the morphological evolutionary behavior of an isolated thin Ge/Si nanoisland (quantum dot) on a rigid substrate exposed to electromigration forces. This morphological evolution is basically induced by the anisotropic surface drift diffusion, driven by the capillary forces, the lattice mismatch stresses, and the wetting potential. In this study, we have mainly focused on the size and shape development kinetics of quantum dots, known as the “Stranski–Krastanov” (SK) morphology, influenced by applied electromigration stresses. Emphasis is given to the effects of rotational symmetry associated with the anisotropic diffusivity in 2D space (i.e., quantum wires in 3D). The pointed bullet-shaped “Stranski–Krastanov” islands with high aspect ratios, ξ = 0.77, are formed at the cathode edge, while the whole nanoisland slightly creeps out of the initial computational domain. The favorable configuration of the Ge20/Si80 alloy test module, which resulted in ζ = 0.37 enhancement in the contour surface area, has a dome shape attached to the [010] top surface of the Si substrate with a zone axis of {010}/⟨001⟩. The anisotropic surface diffusion dyadic has a fourfold rotational symmetry axis [001] lying on the (001) plane of the Si substrate, and its major axis is tilted at about ϕ = 45° from the applied electrostatic field extended along the longitudinal axis [100] of the substrate. This particular experiment resulted in a SK singlet peak with a small satellite with a very small aspect ratio of ≅0.2 that may be appropriate for the conception of quantum optoelectronic devices or inter-band structures to generate photoelectrons having large energy spectra, thereby increasing the efficiency of photovoltaics exposed to solar radiations.

Realizing the air brazing of ZrO2 ceramics through Al metal

The exploration towards cost-effective filler metal for ceramics joining has always been the key issues for ceramics joining. Herein, we reveal that the Al metal prefers to spread on the ZrO2 based ceramic under the air heating condition, due to the geometric limit effects by in-situ formed dense Al2O3 surface. Inspired by this, the joining of ZrO2 based ceramics was realized in air with Al metal as filler, through the diffusion of Al towards ceramic side. The Al element can induce obvious interfacial bonding effect on Al2O3 layer and ZrO2 ceramic, where the hybridization among the Al-p, Zr-d and O-p orbitals plays a key role. The in-situ formed Al2O3 layer on Al filler surface is vital for forming the fine interface (shear strength of ∼36 MPa), which results in the relief of lattice mismatch and peak stress at ceramic-filler metal transition interface.

Liquid phase epitaxy growth of (GdYbBi)3(FeGe)5O12 films for magneto-optical applications

As an important component in magneto-optical devices, bismuth-substituted rare-earth iron garnet films play a significant role in guarantying a unidirectional light propagation in optical communication system. In this study, (GdYbBi)3(FeGe)5O12 film with a thickness of 120 μm was successfully grown by liquid phase epitaxy (LPE) technology. Lattice mismatch and internal stress between the epitaxial film and substrates were discussed in detail. Tested results shown that (GdYbBi)3(FeGe)5O12 films exhibit high crystal quality and large specific faraday rotation angle, which indicate that the prepared (GdYbBi)3(FeGe)5O12 films have a great potential to be used in optical communication system.

Simple model of nitrogen protrusions forming nanostripes within hexagonal FeN on Cu(001)

Hexagonal FeN monolayers on Cu(001) show a stripe pattern composed of dark and bright stripes as observed recently by scanning tunneling microscopy (STM). The nanostripes are formed by more or less protruded nitrogen atoms in the center of iron triangles. Here a simple model is proposed to interpret those results. It uses a planar Fourier analysis with two different wave vectors to calculate small displacements of Fe atoms caused by lattice mismatch stress. The area of displaced Fe atom triangles is used as a measure for the protrusion of N atoms in their center. Proper selection of the wave vectors allows to visualize the dominant protrusions of (3×3) ordered nitrogen atoms. The wave vectors selected are related to Fe configurations which minimize lattice mismatch stress. Hard spheres are used to model Cu-Fe and Fe-Fe interactions in search of a minimal configuration energy. The model explains key elements of the stripe configuration. The model is kept simple, so just the most basic features of the STM experiments are covered. The limits of the model are discussed and ways for extending it are proposed.

(Invited) Stress Simulations of Fins, Wires, and Nanosheets

As the scalability of FinFET architectures is stretched to its limits in the most advanced technologies, industry and research are looking to the next candidates to scale the gate lengths a few nanometers closer to 10nm. Nanosheets and nanowires are such candidates, and specifically the introduction of the former is considered by a major industry player [1]. The inflection point of the transition from fins to sheets and wires depends on multiple trade-offs, of which channel stress is one: stress in the new architectures should preferably match the one in fins to become a viable contender to FinFET technologies. The introduction of stress in fins, wires and sheets, including devices with alternative channel materials, has been studied by several excellent publications from others [2-5], as well as by us [6-8].This work will focus on TCAD simulations of channel stress in fins, wires and sheets with typical 5nm-node dimensions. We focus on stress generation resulting from the following interacting stressors: 1. Lattice mismatch stress resulting from a different Ge composition between the substrate and the channel 2. lattice mismatch stress between the source/drain regions and the substrate (and channel) 3. for the case of wires and sheets, lattice mismatch stress from the sacrificial layers that are grown in between the wires and sheets, and that are removed in the replacement gate module. All simulations are performed with Sentaurus Process [9].For Si0.5Ge0.5 nanowires on a Si0.75Ge0.25 virtual substrate (Fig. 1) with Si0.5Ge0.5 epitaxially grown source/drains, the longitudinal channel stress at the end of processing in the top, middle and bottom wires is plotted in Fig. 2, and compared to the stress in corresponding fin structures. The following observations can be made: 1. Compressive (i.e. negative) channel stress is found, making this configuration suitable for p-type devices. 2. stresses are strongly dependent on the original fin or wire length, as stress relaxation occurs during fin/ wire cut. 3. there is significant difference between the stress in the top, middle and bottom wire, especially for short wire lengths. 4. (absolute) stresses in wires are higher than in fins, thanks to the presence of the sacrificial layers that limit stress relaxation in wires during wire cut [6].Scaling the devices from 8nm-node to 3nm-node dimensions decreases the absolute stress in fins and wires, Fig. 3. However, significant stress values are predicted down to the smallest nodes, especially for nanowires (> 1GPa). For all nodes, the stress in wires outperforms the one in fins by 50-70%.Fig. 4 shows the channel stress in nanowires and sheets versus device width. Moving from wires (i.e. a device width of 7nm) to larger widths, corresponding to sheets, tends to decrease the volume ratio of the source/drain stressor to the channel. As a consequence, lower absolute stresses are predicted for wider sheets, even when the wire/sheet pitch is scaled along with the device width. In general the highest stresses are found when the channels are thin, provided the mechanical stability of the channel is not compromised, which is something that has not been assessed in this work.Finally, the goal of this work is to study one particular concern for source/drain epitaxy in nanowires and nanosheets: in the presence of internal spacers, the source/drain epi starts from the nanowires as well as from the substrate, and may not join perfectly, leading to stress loss (Fig. 5). This work will perform a worst-case estimate of the stress loss in the presence of various defective interfaces. The TCAD results will be compared with experimentally measured strain using nano-beam diffraction [7-8].

Effect of lattice mismatch stress on magnetic domain of epitaxial single crystal (BiTm)3(GaFe)5O12 film

Yttrium iron garnet (YIG) film is a kind of magnetic film and has been investigated extensively because of its excellent magnetic properties and various applications in different fields. Generally, the easy-axis of the film is in-plane and can be changed from in-plane to out-of-plane by introducing some Bi3+ ions into the dodecahedral sites as it has big uniaxial anisotropy, which will be very important in magnetic bubble memories, magneto-optical devices and the new development of spin-wave logic devices. In comparison with many other preparation techniques, the liquid phase epitaxy (LPE) has been consider as a potential method of realizing perpendicular magnetization film due to its big growth-induced anisotropy. However, the LPE technique has more stringent requirements for lattice match between garnet film and gadolinium gallium garnet (GGG) substrate, especially in the growth of thick film. The lattice match is the key factor in LPE growth if the aim of experiment is to achieve a perfect quality and thick film. In most of experiments, there always exists the lattice mismatch between the film and substrate. Owing to the film and substrate have different chemical compositions, their lattice mismatch stress is unavoidable. The purpose of this paper is to investigate the effect of the stress on the anisotropy and then the magnetic domain of (BiTm)3(GaFe)5O12 single crystal film. In our experiment, the monocrystalline (BiTm)3(GaFe)5O12 films are prepared on (111)-oriented GGG substrates by LPE technique and the effect of lattice mismatch stress on the uniaxial anisotropy and magnetic domain are investigated. It is found that the lattice constant of the film is mainly determined by the content of Bi3+ in the film composition. and the increase of Bi3+ content leads to the increase of the film lattice constant, which affects the lattice mismatch stress between film and substrate. The lattice mismatch stress can adjust the perpendicular anisotropy of film which is the main reason for the domain changes. As the mismatch stress changes from tensile stress to compressive stress gradually, the magnetic bubble domain is transformed first into maze domain, and then into the partially striped domain, finally into the completely striped domain. The mismatch tensile stress is an effective method to enhance perpendicular anisotropy, when the growth-induced perpendicular anisotropy is not large enough. The bubble domain can only appear on the film with large tensile stress. The domain size is closely related to the stress. The domain width becomes wider as the mismatch stress becomes larger and it has the smallest domain size as the stress is minimum. These experimental results are very useful in controlling the uniaxial anisotropy and magnetic domain based on the change of the lattice mismatch stress in the growth process.

Enhanced Solar Cell Conversion Efficiency of InGaN/GaN Multiple Quantum Wells by Piezo-Phototronic Effect.

The piezo-phototronic effect is the tuning of piezoelectric polarization charges at the interface to largely enhance the efficiency of optoelectronic processes related to carrier separation or recombination. Here, we demonstrated the enhanced short-circuit current density and the conversion efficiency of InGaN/GaN multiple quantum well solar cells with an external stress applied on the device. The external-stress-induced piezoelectric charges generated at the interfaces of InGaN and GaN compensate the piezoelectric charges induced by lattice mismatch stress in the InGaN wells. The energy band realignment is calculated with a self-consistent numerical model to clarify the enhancement mechanism of optical-generated carriers. This research not only theoretically and experimentally proves the piezo-phototronic effect modulated the quantum photovoltaic device but also provides a great promise to maximize the use of solar energy in the current energy revolution.

Edge Dislocations Triggered Surface Instability in Tensile Epitaxial Hexagonal Nitride Semiconductor.

Understanding the semiconductor surface and its properties including surface stability, atomic morphologies, and even electronic states is of great importance not only for understanding surface growth kinetics but also for evaluating the degree to which they affect the devices' performance. Here, we report studies on the nanoscale fissures related surface instability in AlGaN/GaN heterostructures. Experimental results reveal that edge dislocations are actually the root cause of the surface instability. The nanoscale fissures are initially triggered by the edge dislocations, and the subsequent evolution is associated with tensile lattice-mismatch stress and hydrogen etching. Our findings resolve a long-standing problem on the surface instability in AlGaN/GaN heterostructures and will also lead to new understandings of surface growth kinetics in other hexagonal semiconductor systems.

Stability and controllability of InGaAs/GaAsP wire-on-well (WoW) structure for multi-junction solar cells

Wire on Well (WoW) structure embedded in a matrix is naturally formed by growing InxGa1−xAs/GaAs1−yPy strained multiple quantum wells (MQW) on vicinal substrates and employing triethylgallium (TEGa) as a precursor in low-temperature MOVPE. The structure is useful for the subcell in current-matched mult-junction solar cells with lattice-matched materials because of its ability of band-gap tuning. In this research, high density and uniform In0.30Ga0.70As/GaAs0.6P0.4 WoW was obtained up to 200 stacks and its structure was analyzed by X-ray diffraction reciprocal space mapping, atomic force microscopy and scanning transmission electron microscopy. The structure of the wire can be controlled by changing the equivalent layer thicknesses of In0.30Ga0.70As and GaAs0.6P0.4. The photoluminescence peak from the WoW shifted according to the size of InGaAs wires and the intensity was dependent on the accumulation of lattice-mismatch stress.

(Invited) Modeling Extended Defects in Semiconductor Devices

We perform analysis of several key aspects of the extended defect formation and their impact on silicon and GaN transistors. Heterogeneous epitaxy has been an enabling technique in transistor design since 90 nm technology node. The most widely used stress engineering technique is based on introducing crystal lattice mismatch stress by growing SiGe on Si. Depending on Ge content and on the size and shape of the selectively grown SiGe islands, the lattice mismatch stress can be high enough to introduce edge dislocations and stacking faults. Once the dislocations are created, they can move, driven by stress gradients towards more energetically favorable locations. An example of creating geometrical features to attract dislocations towards certain area has been demonstrated experimentally for epitaxial SiGe layers exceeding critical thickness on non-planar Si surfaces [1]. We reproduce such behavior by numerical minimization of elastic strain energy of an ensemble of {111} stacking faults (Fig. 1). Whenever dislocations manage to escape such herding and encroach into sensitive transistor areas, we perform quantum transport analysis to estimate the impact of a dislocation on electron scattering, on-state and off-state currents for Si nanowires with 5nm design rules. Another area where extended defect monitoring is essential is the GaN power switches. To achieve low buffer leakage in AlGaN/GaN HEMT for high voltage applications, it has been proposed to intentionally dope the GaN buffer with carbon [2]. This creates acceptor traps in the buffer to pin the Fermi Level at ~0.86 eV above the valence band [3]. A p-type buffer is thus formed and isolated from the Two-Dimensional Electron Gas (2DEG), which aggravates current collapse [3][4]. However, experimental results show that the magnitude of current collapse is less than suggested by modeling which can be attributed to the buffer being connected to the 2DEG through threading dislocations [3]. In this work, we perform 3D TCAD analysis of the impact of threading dislocations on the buffer trapping/de-trapping and current collapse. [1] R. Gatti, F. Boioli, M. Grydlik, M. Brehm, H. Groiss et al., Appl. Phys. Lett., 98, 121908 (2011) [2] E. Bahat-Treidel, F. Brunner, O. Hilt et al., IEEE Trans. Electron Devices, 57(11), 3050–3058 (2010) [3] M. J. Uren, M. Silvestri, M. Cäsar, G. A. M. Hurkx, J. A. Croon, J. Šonský, and M. Kuball, IEEE Electron Device Lett. 35(3), 327–329 (2014) [4] M. J. Uren, J. Möreke, and M. Kuball, IEEE Trans. Electron Devices 59 (12), 3327–3333 (2012) Fig. 1. Dislocations in epitaxial SiGe layer move towards the bottom of a V-shaped trench in Si wafer (a). Each additional dislocation reduces the total elastic strain energy of the structure (b). Figure 1

(Invited) Modeling Extended Defects in Semiconductor Devices

The most widely used in the industry stress engineering technique is based on introducing crystal lattice mismatch stress by growing SiGe on Si. For the power switches, GaN is epitaxially grown on an AlGaN buffer on top of Si wafer. The lattice mismatch stress can be high enough to introduce edge dislocations and stacking faults. We perform analysis of several key aspects of the extended defect formation and their impact on silicon and GaN transistors. We demonstrate modeling methodology to determine where a stacking fault is going to move driven by a stress gradient. Once a dislocation has found its energetically favorable location, it can be either inside or outside of the area sensitive to transistor performance. We explore the impact of a dislocation on the carrier scattering for the on-state current of advanced Si CMOS transistors and the impact of threading dislocations on power GaN switches.

Structural properties of In0.53Ga0.47As epitaxial films grown on Si (111) substrates by molecular beam epitaxy

In0.53Ga0.47As epitaxial films are grown on 2-inch diameter Si (111) substrates by growing a low-temperature In0.4Ga0.6As buffer layer using molecular beam epitaxy. The effect of the buffer layer thickness on the as-grown In0.53Ga0.47As films is characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy and transmission electron microscopy (TEM). It is revealed that the crystalline quality and surface morphology of as-grown In0.53Ga0.47As epilayer are strongly affected by the thickness of the In0.4Ga0.6As buffer layer. From TEM investigation, we understand that the type and the distribution of dislocations of the buffer layer and the as-grown In0.53Ga0.47As film are different. We have demonstrated that the In0.4Ga0.6As buffer layer with a thickness of 12nm can advantageously release the lattice mismatch stress between the In0.53Ga0.47As and Si substrate, ultimately leading to a high-quality In0.53Ga0.47As epitaxial film with low surface roughness.

High mobility AlGaN/GaN heterostructures grown on Si substrates using a large lattice-mismatch induced stress control technology

A large lattice-mismatch induced stress control technology with a low Al content AlGaN layer has been used to grow high quality GaN layers on 4-in. Si substrates. The use of this technology allows for high mobility AlGaN/GaN heterostructures with electron mobility of 2040 cm2/(V·s) at sheet charge density of 8.4 × 1012 cm−2. Strain relaxation and dislocation evolution mechanisms have been investigated. It is demonstrated that the large lattice mismatch between the low Al content AlGaN layer and AlN buffer layer could effectively promote the edge dislocation inclination with relatively large bend angles and therefore significantly reduce the dislocation density in the GaN epilayer. Our results show a great potential for fabrication of low-cost and high performance GaN-on-Si power devices.

Some methods of inducing high–coercivity state in epitaxial magnetic garnet films for thermomagnetic recording

Results of studying coercive force, optical absorption and lattice mismatch in single−crystal epitaxial magnetic garnet films are presented. It is shown that the reason of high values of both coercivity and optical absorption are the oxygen vacancies compensating Ca2+ ions and lattice mismatch stress. Methods of inducing high−coercivity state in Bi−containing garnet films through doping by bivalent impurity ions, through mismatch stress or through treatment in negative corona discharge are proposed. Merits and demerits of these methods are discussed and their comparison is carried out.

Mechanical property effects of Si1 − xGex channel and stressed contact etching stop layer on nano-scaled n-type metal–oxide–semiconductor field effect transistors

This study demonstrated that advanced strained engineering in contact etching stop layer (CESL) combined with silicon germanium (Si1−xGex) stressors can be efficiently utilized to enhance the performance of devices. Lattice mismatch stress was induced to establish an Si1−xGex channel integrated with intrinsic stress of CESL, which consists of multiple stressors, to analyze the stress contour of the concerned channel in n-type metal–oxide–semiconductor field effect transistors (nMOSFETs) by three-dimensional (3D) finite element analysis (FEA). The types of intrinsic CESL stress considered in this study were tensile (1.1GPa) (t-CESL) and compressive (−2.0GPa) (c-CESL). Germanium mole fractions, including 0%, 22.5%, and 25%, utilized in the Si1−xGex channel were selected to carefully analyze their impact on the Si1−xGex channel. The effect of channel geometries, which are composed of aspect ratio of length and width, was considered as well. Results reveal that the stress components of the Si1−xGex channel increases significantly when the amount of Si1−xGex layer increases. A change in the length and width of the channel induces inversion in the Si1−xGex channel regarding stress conventions in the direction of the channel's length and width. Results predicted by the proposed FEA were consistent with experimental data as validated by the nMOSFET with an Si0.775Ge0.225 channel. Comparison of the simulation results of FEA with two-dimensional (2D) and 3D models was performed. The results show that wide gate width in the 3D model can induce a response to the calculated results similar to that obtained in a 2D situation.

Design of high-coercivity epitaxial magnetic garnet films for thermomagnetic recording and nanotechnology

Tuning the magnetic hysteresis and optical absorption in single crystal epitaxial magnetic garnet films is investigated. It is demonstrated that high values of coercivity and optical absorption are caused by lattice mismatch stress and/or oxygen vacancies which compensate calcium anions in Ca-containing garnet films. Several methods for enhancing coercivity in Bi-containing films are studied: by doping bivalent impurity anions, by mismatch stress and by treatment in negative corona discharge. Optimization and comparative analysis of these methods are carried out discussing their pros and cons.

Properties of N-Polar GaN Films Grown by MOCVD on C-Face 6H-SiC Substrate

High quality N-polar GaN films were grown by MOCVD on C-face 6H-SiC substrate etched by KOH eutectics at 300°C for 5min. A 50 nm high-temperature AlN buffer layer was used to release the lattice mismatch stress between GaN and SiC substrate. The N-polar GaN films grow on the C-face 6H-SiC substrate etched by KOH eutectics have a high crystalline quality and smooth surface. The full-width-at-half-maximum (FWHM) of (002) and (102) XRD spectra were 347.4 and 501.5 arcsec., respectively. The root-mean-square (RMS) of 3μm×3μm is 0.666 nm. The luminescence property of the N-polar GaN films was studied. The band-edge emission of photoluminescence spectra was at 364.6 nm with weak yellow luminescence near 560 nm. The stress in the films was also calculated from Raman spectra. The results indicated a tensile stress in the N-polar GaN films, which is mainly caused by mismatch of thermal expansion coefficient between GaN and SiC substrate.

Spectroscopic analysis of phase constitution of high quality VO2 thin film prepared by facile sol-gel method

VO2 thin films with large-area were prepared on Al2O3 substrates by a simple sol-gel method. After an annealing treatment under low vacuum condition, all the VO2 films showed a preferred growth direction and exhibited excellent semiconductor-metal transition (SMT) characteristics. The structure and electrical properties of the obtained VO2 films were investigated systematically. Raman spectra, X-ray diffraction and X-ray absorption spectra measurements pointed out that the VO2 film on ${\rm A}{\rm l}_{\rm 2} {\rm O}_{\rm 3} ( {{\rm 10}\overline {\rm 1} {\rm 0}})$Al2O3(101¯0) substrate showed a M1 phase instead of M2 phase as reported in previous studies. Based on the experiment results, it was suggested that the strained structure of oriented VO2 films could be a mechanism for the formation of the intermediate M2 phase, whereas it is difficult to access the pure M2 phase of undoped VO2 films. VO2 film on ${\rm A}{\rm l}_{\rm 2} {\rm O}_{\rm 3} \left( {{\rm 10}\overline {\rm 1} {\rm 0}} \right)$Al2O3101¯0 substrate showed a lower SMT temperature compared to VO2 film on Al2O3 (0001), which can be mostly attributed to the differences of both lattice mismatch and thermal stress. The present results confirm and make clear the relevance of the substrate orientation in the growth of VO2 film and their different contributions to the SMT characteristics in vanadate systems.