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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.

No MeSH data available.


Related in: MedlinePlus

The calculated (002) 2θ/ω XDPs for GaN NWs. (a) The influence of the deformation magnitude () at the NW/substrate interface. (b) The influence of the deformation relaxation depth (LR). The insets show the deformation profiles (defined by Equation 3) used for the calculation. The dashed line in (a) shows the XDP determined only by the size effect (without deformation).
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Fig2: The calculated (002) 2θ/ω XDPs for GaN NWs. (a) The influence of the deformation magnitude () at the NW/substrate interface. (b) The influence of the deformation relaxation depth (LR). The insets show the deformation profiles (defined by Equation 3) used for the calculation. The dashed line in (a) shows the XDP determined only by the size effect (without deformation).

Mentions: Different types of deformation lead to specific changes in the XDP. In Figure 2, we demonstrate a calculated (002) 2θ/ω XDP for a 500-nm-long GaN NWs array affected only by micro-deformation ε//(z). We show how the magnitude of initial deformation (caused by the lattice misfit at the NW/substrate interface) and the deformation relaxation depth LR (dependent on the aspect ratio of NW) contribute to the XDP. It is shown (Figure 2a) that for LR = const, the increase of magnitude of micro-deformation at the NW/substrate interface leads to asymmetrical XDP broadening, whereas the deformation sign (tensile or compressive deformation) defines the broadening direction. Similarly (Figure 2b), for we demonstrate that the magnitude of deformation relaxation depth (LR) is another source of asymmetrical XDP broadening. Moreover, when LR exceed some critical value (for a specific aspect ratio of NW), which leads to the XDP shift, we can conclude on the presence of macro-deformation ε/. Thus, the value of this deformation can be estimated directly from the magnitude of the XDP shift. It should be noted that the asymmetric broadening and shift of XDP for GaN NWs was observed experimentally in [3,4].Figure 2


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. (a) The influence of the deformation magnitude () at the NW/substrate interface. (b) The influence of the deformation relaxation depth (LR). The insets show the deformation profiles (defined by Equation 3) used for the calculation. The dashed line in (a) shows the XDP determined only by the size effect (without deformation).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig2: The calculated (002) 2θ/ω XDPs for GaN NWs. (a) The influence of the deformation magnitude () at the NW/substrate interface. (b) The influence of the deformation relaxation depth (LR). The insets show the deformation profiles (defined by Equation 3) used for the calculation. The dashed line in (a) shows the XDP determined only by the size effect (without deformation).
Mentions: Different types of deformation lead to specific changes in the XDP. In Figure 2, we demonstrate a calculated (002) 2θ/ω XDP for a 500-nm-long GaN NWs array affected only by micro-deformation ε//(z). We show how the magnitude of initial deformation (caused by the lattice misfit at the NW/substrate interface) and the deformation relaxation depth LR (dependent on the aspect ratio of NW) contribute to the XDP. It is shown (Figure 2a) that for LR = const, the increase of magnitude of micro-deformation at the NW/substrate interface leads to asymmetrical XDP broadening, whereas the deformation sign (tensile or compressive deformation) defines the broadening direction. Similarly (Figure 2b), for we demonstrate that the magnitude of deformation relaxation depth (LR) is another source of asymmetrical XDP broadening. Moreover, when LR exceed some critical value (for a specific aspect ratio of NW), which leads to the XDP shift, we can conclude on the presence of macro-deformation ε/. Thus, the value of this deformation can be estimated directly from the magnitude of the XDP shift. It should be noted that the asymmetric broadening and shift of XDP for GaN NWs was observed experimentally in [3,4].Figure 2

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