Nucleation mechanism of GaN nanowires grown on (111) Si by molecular beam epitaxy

Abstract

We have performed a real-time in situ x-ray scattering study of the nucleation of GaN nanowires grown by plasma-assisted molecular beam epitaxy on AlN(0001)/Si(111). The intensity variation of the GaN diffraction peak as a function of time was found to exhibit three different regimes: (i) the deposition of a wetting layer, which is followed by (ii) a supralinear regime assigned to nucleation of almost fully relaxed GaN nanowires, eventually leading to (iii) a steady-state growth regime. Based on scanning electron microscopy and electron microscopy analysis, it is proposed that the granular character of the thin AlN buffer layer may account for the easy plastic relaxation of GaN, establishing that three-dimensional islanding and plastic strain relaxation of GaN are two necessary conditions for nanowire growth.

GaN based nanorods for solid state lighting

“…Landré et al also pointed out that the morphology of the AlN buffer, in particular the grain size, is a key parameter for subsequent GaN nanorod growth. 33 It is proposed that the granular character of the thin AlN buffer layer may account for the easy plastic relaxation of GaN, establishing that three-dimensional islanding and plastic strain relaxation of GaN are two necessary conditions for nanorod growth. Besides, the AlN interlayer was also found to be able to improve the orientation of the GaN nanorod grown on Si (111).…”

“…33,36 Furthermore, Consonni et al free energy which explains the transition from GaN nanotruncated pyramidal structure to vertical nanorod growth. 37 They observed several consecutive shape transitions from spherical caps through truncated-to full-pyramid-shaped islands at the onset of the nucleation process (shown in Fig.…”

Electrically driven polarized single-photon emission from an InGaN quantum dot in a GaN nanowire

“…GaN and In(Ga)N nanowires can be epitaxially grown catalyst free on silicon substrates with aerial density in the range of 10 8 -10 11 cm À 2 and lengths up to a few micrometres [23][24][25][26][27][28][29][30][31][32] . The nanowires grow vertically in the wurtzite crystalline form and optical emission from them in the spectral range of 366-700 nm has been recorded by varying the In composition.…”

“…The nanowires grow vertically in the wurtzite crystalline form and optical emission from them in the spectral range of 366-700 nm has been recorded by varying the In composition. Extensive structural characterization indicates that the nanowires are relatively free of extended defects 23,24,[27][28][29][31][32][33][34] . They can be doped p-and n-type with suitable dopant species up to levels similar to those achieved in planar structures.…”

Influence of the adatom diffusion on selective growth of GaN nanowire regular arrays

“…10-12͒ and NW ensembles 13,14 has been proven. However, the processes of nucleation [15][16][17][18][19] and diffusion of adatoms [20][21][22][23] on the NW still represent interesting and lively discussion subjects as not all the aspects have been clarified. In addition, the understanding of the growth leads to further improvements of sample quality and of the control over the structures, which in turn is beneficial for device performances.…”