The influence of AlN buffer over the polarity and the nucleation of self-organized GaN nanowires

Abstract

International audienc

Eutectic Formation, V/III Ratio, and Controlled Polarity Inversion in Nitrides on Silicon

“…A potential source of such clustering could be the formation of droplets, which have been frequently reported for Al‐rich growth conditions . Fluctuations in the Al–Si eutectic “layer” thickness and in the associated Si distribution may be either a direct result of or a precursor to droplet formation.…”

“…Thus, the ability to induce polarity inversion would be useful for obtaining metal‐polar films and nanowires. This may be especially important for nanowires, which are advantageous due to their lower defect densities, as spontaneously grown NWs are typically N‐polar, and because selective area nanowire growth on Si is facilitated by N‐polarity . In fact controlled polarity inversion has already been demonstrated both for epitaxial AlN layers and for spontaneously nucleated GaN nanowires using an oxidized interlayer.…”

“…In fact, rather than an SiN x layer, the formation of Al–Si eutectic has been reported for PAMBE growth of AlN on both Si(111) and SiC substrates, and it has been proposed that the eutectic is responsible for a liquid Al–Si layer floating on the AlN surface during growth under Al‐rich conditions …”

Chemical composition fluctuations and strain relaxation in InGaN nanowires: The role of the metal/nitrogen flux ratio

“…Before GaN NW growth, a thin AlN buffer layer was deposited, about 3-5 nm thick, in order to improve NW twist [18] and tilt [19], while resulting in a homogeneous NW density all over the wafer surface. Such GaN NWs self-nucleated on an AlN/Si(111) substrate mostly exhibit N-polarity [20,21], making the InGaN NW section grown on top of them also N-polar.…”

GaN nanowires on diamond

“…It should be mentioned that some groups have observed a mixture of polarities within a single NW [51][52][53]. It can not be ruled out that this also occurs for some SAG NWs on diamond Fig.…”