کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1522727 | 1511822 | 2013 | 6 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Self-catalyst growth of novel GaN nanowire flowers on Si (111) using thermal evaporation technique Self-catalyst growth of novel GaN nanowire flowers on Si (111) using thermal evaporation technique](/preview/png/1522727.png)
We investigated the effect of substrate temperature on nanowire (NW) flower GaN epitaxial layers grown on catalyst-free Si (111) through physical vapor deposition via the thermal evaporation of GaN powder at 1150 °C in the absence of NH3 gas. The NW flowers were grown at various substrate temperatures from 1000 °C to 1100 °C for 60 min in N2 ambient. The surface morphology as well as the structural and optical properties of GaN NW flowers were examined by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, X-ray diffraction, and photoluminescence (PL). The results showed that the increase in substrate temperature resulted in a variation in crystal quality and surface morphology. SEM showed that the substrate temperature has a stronger effect on NW density and growth rate with respect to time. The average length of GaN flowers is estimated to be longer than 300 μm after 1 h at 1100 °C, which corresponds to a fast growth rate of more than 200 μm h−1 at all substrate temperatures. The PL measurements showed strong near-band-edge (NBE) emission with a weak deep level emission. The green-yellow emission (GYE) can be attributed to N vacancies or to the VGa–ON-complexes. The NBE peak exhibited a redshift with increasing substrate temperature, which results from the increase in strain level. The growth mechanism of the polycrystalline GaN NWs was also discussed.
► GaN nanowired flowers were grown on free-catalysts Si (111) using PVD.
► A higher temperature, higher uniformity, larger lengths and diameters of the NW flowers.
► As substrate temperature increases the diameters and growth rate of NWs increases.
► A lower temperature resulted in a high density and good crystal quality of GaN NWs.
► The increase in substrate temperature increased the redshift in UV band emission.
Journal: Materials Chemistry and Physics - Volume 139, Issues 2–3, 15 May 2013, Pages 459–464