While the thermodynamic nonequilibrium properties of nanoparticles are being extensively studied, the thermodynamic nonequilibrium properties of their counterpart: nanocavities, however, are less noticed. Here, we systematically review and comprehensively model the recently published results on the newly-found thermodynamic nonequilibrium properties of nanocavities in covalently bound materials during energetic beam irradiation. We also review and model the thermodynamic nonequilibrium properties of nanoparticles. The review and modelling not only demonstrates the novel nonequilibrium properties of such an open-volume nanostructure during external excitation but also gives a deep insight into the nonequilibrium thermodynamics of amorphous structures and the difference in the behaviours of defects in crystalline and in amorphous silicon. Especially, the review and modelling leads to two new concepts: • anti-symmetry relation between a nanoparticle and a nanocavity • energetic beam induced-soft mode and lattice instability in condensed matter which reveals that structure of a condensed matter would be unstable not only at nanosize scale but also at a nanotime scale in general. It is also reveals that such nanoinstabilities would be more pronounced in an amorphous structure than in a crystalline structure.

近年来，GaN基相关材料的量子点生长成为半导体材料研究的一个热点，尤其是用MOCVD方法生长GaN基自组装量子点占了相当的比例，因此相关的文献较多，但综述性文章却不多见。鉴于此，本文综述了用MOCVD制备GaN基量子点的不同实验方法，并对影响量子点生长的实验条件和参数做了简要的分析，希望能够对相关的实验研究工作提供一些参考。

An internal shrinkage of nanocavity in silicon was in situ observed under irradiation of energetic electron on electron transmission microscopy. Because there is no addition of any external materials to cavity site, a predicted nanosize effect on the shrinkage was observed. At the same time, because there is no ion cascade effect as encountered in the previous ion irradiation-induced nanocavity shrinkage experiment, the electron irradiation-induced instability of nanocavity also provides a further more convincing evidence to demonstrate the predicted irradiation-induced athermal activation effect.

Single wall carbon nanotubes are fabricated by a long pulse and high power Nd:YAG laser ablation from a solid composite target consisting of graphite and bimetallic catalyst at room temperature without any carrying gas flow. The results demonstrated that the technique could eliminate several processing parameters currently used for SWNT fabrication via laser ablation process. Most importantly, the new process can produce well-dispersed, straight, and clean SWNTs, rather than bundled and deformed SWNTs coated with bimetals and amorphous carbon nanoparticles. A mechanism is suggested for such an improved SWNT growth.

The solid phase epitaxial regrowth of structurally modified amorphous silicon created by self-ion implantation into nanovoided crystalline silicon is investigated. It is demonstrated that although the modified amorphous silicon is fully reconstructed into single crystal during the epitaxial regrowth, both activation energy and atom attempt frequency for the regrowth are much higher than those of the typical amorphous Si induced by self-ion implantation into Si wafer without nanovoids. The novel regrowth kinetics indicates that the modified amorphous silicon would contain a very high concentration of dangling bonds, which are believed to result from dissociation of the nanovoids originally metastablized in crystalline silicon. The unparalleled sensitivity of SPEG provides an effective and simple way to detect and characterize the subtle structural changes at nanometer scale in amorphous Si.

Structural instability of single wall carbon nanotube under electron beam irradiation was investigated by our developed in-situ transmission electron microscopy observation technique. It was observed that the nanotube shrunk and necked in diameter gradually and the curved nanotube shrunk faster in axis direction than straight one with increasing of electron dose during the irradiation. Such athermally induced structural instabilities can be well accounted for by completely new concepts of the nano curvature and the energetic beaminduced soft mode and lattice instability as we recently proposed.

During attempts to fabricate ZnO nanowires, we accidentally observed the growth of SiOx nanowires on Au-coated Si substrate. Detailed characterizations on the resulting nanowires were carried out by field-emission scanning electron microscopy, electron microprobe analysis, transmission electron microscopy, selective area electron diffraction, energy-dispersed X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The resulting nanowires have a Si-to-O ratio of 1:1.63 and a diameter of 50-300 nm. It was found that the presence of graphite powder in the growth furnace was critical. A systematic investigation of how the growth conditions, such as the growth temperature, the oxygen-to-Ar carrier gas ratio, and growth time, affect the formation of SiOx nanowires was performed. Higher growth temperature and appropriate low oxygen gas flow helped to promote long nanowire growth. The diameters of the nanowires increased with growth time. It was demonstrated that the formation of the SiOx nanowires was due to a solid-liquid-solid mechanism, and the locally catalytic oxidation of CO by Au nanoclusters may play a role in accelerating nanowire formation.

A critical modelling of the nonequilibrium thermodynamic properties of nanocavities and nanoparticles is presented. We first correlate our newly observed experimental results about nanocavities in silicon that can shrink during energetic-beam irradiation with the available experimental phenomena of nanoparticle instabilities. Several newconcepts, which challenge our current understanding of science, are put forward and a novel universal antisymmetry relationship between a nanoparticle and a nanocavity in condensed matter is revealed.

With a series of supportive experimental phenomena as induced by ion beam bombardment, energetic beam induced athermal activation process in Si is demonstrated. This is correlated with phenomena induced by ultrafast cnergy exchange in condensed matter in general. A critical modelling is presented on the above process and a universal concept: the ultrafast energy exchangc-induced soft mode of phonons and the lattice instability in condensed matter are proposed.

Si containing a band of nanocavities has been irradiated with Si1 ions at elevated temperatures to study interactions of irradiation-induced defects with open volume defects. For irradiation at 100℃, nanocavities are shown to be preferential nucleation sites for amorphization. It is proposed that this behavior occurs to minimize the local free energy, whereby less dense amorphous Si is free to expand into the cavity open volume. Furthermore, for irradiation at 300℃, cavities are very efficient sinks for Si interstitials during irradiation, leaving a region denuded of interstitial-based clusters surrounding each nanocavity.