Effect of an oxide cap layer and fluorine implantation on the metal-induced lateral crystallization of amorphous silicon

In this work, we investigate the effect of oxide cap layer on the metal-induced lateral crystallization (MILC) of amorphous silicon. The MILC is characterized at temperatures in the range 550 to 428°C using Nomarski optical microscopy and Raman spectroscopy. It is shown that better lateral crystallization is obtained when the oxide cap layer is omitted, with the crystallization length increasing by 33% for a 15 hour anneal at 550°C. A smaller increase of about 10% is seen at lower temperatures between 525°C and 475°C and no increase is seen below 450°C. It is also shown that the detrimental effect of the oxide cap layer can be dramatically reduced by giving samples a fluorine implant prior to the MILC anneal. Raman spectroscopy shows that random grain growth is significantly less for unimplanted samples without an oxide cap and also for fluorine implanted samples both with and without an oxide cap. The crystallization length improvement for samples without an oxide cap layer is explained by the elimination of random grain crystallization at the interface between the amorphous silicon and the oxide cap layer

Phantom Energy Accretion onto Black Holes in Cyclic Universe

Black holes pose a serious problem in the cyclic or oscillating cosmology. It is speculated that, in the cyclic universe with phantom turnarounds, black holes will be torn apart by the phantom energy before turnaround before they can create any problems. In this paper, using the mechanism of the phantom accretion onto black holes, we find that black holes do not disappear before the phantom turnaround. But the remanent black holes will not cause any problems due to the Hawking evaporation.Comment: 8 pages, no figure; typographical errors are correcte

Intrinsic Cavity QED and Emergent Quasi-Normal Modes for Single Photon

We propose a special cavity design that is constructed by terminating a one-dimensional waveguide with a perfect mirror at one end and doping a two-level atom at the other. We show that this atom plays the intrinsic role of a semi-transparent mirror for single photon transports such that quasi-normal modes (QNM's) emerge spontaneously in the cavity system. This atomic mirror has its reflection coefficient tunable through its level spacing and its coupling to the cavity field, for which the cavity system can be regarded as a two-end resonator with a continuously tunable leakage. The overall investigation predicts the existence of quasi-bound states in the waveguide continuum. Solid state implementations based on a dc-SQUID circuit and a defected line resonator embedded in a photonic crystal are illustrated to show the experimental accessibility of the generic model.Comment: 4 pages,5 figures, Comments welcom

Binomial coefficients, Catalan numbers and Lucas quotients

Let $p$ be an odd prime and let $a,m$ be integers with $a>0$ and $m \not\equiv0\pmod p$. In this paper we determine $\sum_{k=0}^{p^a-1}\binom{2k}{k+d}/m^k$ mod $p^2$ for $d=0,1$; for example, $$\sum_{k=0}^{p^a-1}\frac{\binom{2k}k}{m^k}\equiv\left(\frac{m^2-4m}{p^a}\right)+\left(\frac{m^2-4m}{p^{a-1}}\right)u_{p-(\frac{m^2-4m}{p})}\pmod{p^2},$$ where $(-)$ is the Jacobi symbol, and $\{u_n\}_{n\geqslant0}$ is the Lucas sequence given by $u_0=0$, $u_1=1$ and $u_{n+1}=(m-2)u_n-u_{n-1}$ for $n=1,2,3,\ldots$. As an application, we determine $\sum_{0<k<p^a,\, k\equiv r\pmod{p-1}}C_k$ modulo $p^2$ for any integer $r$, where $C_k$ denotes the Catalan number $\binom{2k}k/(k+1)$. We also pose some related conjectures.Comment: 24 pages. Correct few typo

A model metal potential exhibiting polytetrahedral clusters

Putative global minima have been located for clusters interacting with an aluminium glue potential for N<190. Virtually all the clusters have polytetrahedral structures, which for larger sizes involve an ordered array of disclinations that are similar to those in the Z, H and sigma Frank-Kasper phases. Comparisons of sequences of larger clusters suggest that the majority of the global minima will adopt the bulk face-centred-cubic structure beyond N=500.Comment: 14 pages, 7 figure

Localization of Relative-Position of Two Atoms Induced by Spontaneous Emission

We revisit the back-action of emitted photons on the motion of the relative position of two cold atoms. We show that photon recoil resulting from the spontaneous emission can induce the localization of the relative position of the two atoms through the entanglement between the spatial motion of individual atoms and their emitted photons. The result provides a more realistic model for the analysis of the environment-induced localization of a macroscopic object.Comment: 8 pages and 4 figure