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High-resolution X-ray diffraction analysis of strain distribution in GaN nanowires on Si(111) substrate.

Stanchu H, Kladko V, Kuchuk AV, Safriuk N, Belyaev A, Wierzbicka A, Sobanska M, Klosek K, Zytkiewicz ZR - Nanoscale Res Lett (2015)

Bottom Line: The calculations are performed by using kinematical theory of X-ray diffraction and assuming the deformation decays exponentially from the NW/substrate interface.Also, we demonstrate that macro-deformation leads to XDP shift, whereas micro-deformations are the cause of XDP's asymmetry and its symmetrical broadening.A good correlation between calculated and experimental XDP from self-assembled GaN NWs on Si(111) substrate was achieved by taking into account all parameters of micro- and macro-deformation profiles.

View Article: PubMed Central - PubMed

Affiliation: V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Pr. Nauky 45, Kyiv, 03028 Ukraine.

ABSTRACT
In this work, the influence of micro- and macro-deformation profiles in GaN nanowires (NWs) on the angular intensity distribution of X-ray diffraction are studied theoretically. The calculations are performed by using kinematical theory of X-ray diffraction and assuming the deformation decays exponentially from the NW/substrate interface. Theoretical modeling of X-ray scattering from NWs with different deformation profiles are carried out. We show that the shape of the (002) 2θ/ω X-ray diffraction profile (XDP) is defined by initial deformation at the NW's bottom and its relaxation depth given by the decay depth of the exponential deformation profile. Also, we demonstrate that macro-deformation leads to XDP shift, whereas micro-deformations are the cause of XDP's asymmetry and its symmetrical broadening. A good correlation between calculated and experimental XDP from self-assembled GaN NWs on Si(111) substrate was achieved by taking into account all parameters of micro- and macro-deformation profiles.

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The calculated (002) 2θ/ω XDPs for GaN NWs affected by the micro-deformationεIII(z). The deformation distribution profiles of εIII(z) used for XDP calculation were defined by Equation 3 and are shown in the inset.
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Fig3: The calculated (002) 2θ/ω XDPs for GaN NWs affected by the micro-deformationεIII(z). The deformation distribution profiles of εIII(z) used for XDP calculation were defined by Equation 3 and are shown in the inset.

Mentions: Next, we analyze the influence of only micro-deformation ε///(z) (caused by the elastic strain relaxation at the free NW's surface) on the XDP's shape. According to the definition, this unsigned deformation ε///(z) is the deformation fluctuation around the ε//(z), and it is described by the same law (see Equation 3). Thus, for LR = const and we calculated (002) 2θ/ω XDP for a 500-nm-long GaN NWs array affected only by micro-deformation ε///(z). It is shown (Figure 3) that the increase of ε///(z) magnitude leads only to symmetrical XDP broadening. It should be noted that coalescence of NWs and lattice distortion have a strong influence on deformation profile of ε///(z) [8,13]. Actually, all kinds of deformations are not independent, and a nonlinear change of ε///(z) deformation leads to an appearance of ε//(z) deformation. Moreover, the increase of micro-deformation (ε//(z)) relaxation depth LR leads to the appearance of a macro-deformation (ε/). Thus, to fit the theoretical XDP from GaN NWs to the experimental one, the distribution of micro- and macro-deformation profiles should be taken into account.Figure 3


High-resolution X-ray diffraction analysis of strain distribution in GaN nanowires on Si(111) substrate.

Stanchu H, Kladko V, Kuchuk AV, Safriuk N, Belyaev A, Wierzbicka A, Sobanska M, Klosek K, Zytkiewicz ZR - Nanoscale Res Lett (2015)

The calculated (002) 2θ/ω XDPs for GaN NWs affected by the micro-deformationεIII(z). The deformation distribution profiles of εIII(z) used for XDP calculation were defined by Equation 3 and are shown in the inset.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385025&req=5

Fig3: The calculated (002) 2θ/ω XDPs for GaN NWs affected by the micro-deformationεIII(z). The deformation distribution profiles of εIII(z) used for XDP calculation were defined by Equation 3 and are shown in the inset.
Mentions: Next, we analyze the influence of only micro-deformation ε///(z) (caused by the elastic strain relaxation at the free NW's surface) on the XDP's shape. According to the definition, this unsigned deformation ε///(z) is the deformation fluctuation around the ε//(z), and it is described by the same law (see Equation 3). Thus, for LR = const and we calculated (002) 2θ/ω XDP for a 500-nm-long GaN NWs array affected only by micro-deformation ε///(z). It is shown (Figure 3) that the increase of ε///(z) magnitude leads only to symmetrical XDP broadening. It should be noted that coalescence of NWs and lattice distortion have a strong influence on deformation profile of ε///(z) [8,13]. Actually, all kinds of deformations are not independent, and a nonlinear change of ε///(z) deformation leads to an appearance of ε//(z) deformation. Moreover, the increase of micro-deformation (ε//(z)) relaxation depth LR leads to the appearance of a macro-deformation (ε/). Thus, to fit the theoretical XDP from GaN NWs to the experimental one, the distribution of micro- and macro-deformation profiles should be taken into account.Figure 3

Bottom Line: The calculations are performed by using kinematical theory of X-ray diffraction and assuming the deformation decays exponentially from the NW/substrate interface.Also, we demonstrate that macro-deformation leads to XDP shift, whereas micro-deformations are the cause of XDP's asymmetry and its symmetrical broadening.A good correlation between calculated and experimental XDP from self-assembled GaN NWs on Si(111) substrate was achieved by taking into account all parameters of micro- and macro-deformation profiles.

View Article: PubMed Central - PubMed

Affiliation: V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine, Pr. Nauky 45, Kyiv, 03028 Ukraine.

ABSTRACT
In this work, the influence of micro- and macro-deformation profiles in GaN nanowires (NWs) on the angular intensity distribution of X-ray diffraction are studied theoretically. The calculations are performed by using kinematical theory of X-ray diffraction and assuming the deformation decays exponentially from the NW/substrate interface. Theoretical modeling of X-ray scattering from NWs with different deformation profiles are carried out. We show that the shape of the (002) 2θ/ω X-ray diffraction profile (XDP) is defined by initial deformation at the NW's bottom and its relaxation depth given by the decay depth of the exponential deformation profile. Also, we demonstrate that macro-deformation leads to XDP shift, whereas micro-deformations are the cause of XDP's asymmetry and its symmetrical broadening. A good correlation between calculated and experimental XDP from self-assembled GaN NWs on Si(111) substrate was achieved by taking into account all parameters of micro- and macro-deformation profiles.

No MeSH data available.


Related in: MedlinePlus