Strain and Phonon Confinement in Self－Assembled Ge Quantum Dot Superlattices Superlattices ＊

Raman scattering measurements were carried out in self-assembled Ge quantum dot superlattices grown bymolecular beam epitaxy. The characteristics of the Ge-Ge, Si-Ge, Si-SiLoc and Si-Si peaks were investigated,especially the Ge-Ge optical phonon frequency shift was emphasized, which was tuned by the phonon confinementand strain effects. The experimentally observed frequency shift values of the Ge-Ge peak frequency caused byoptical phonon confinement and strain in Ge quantum dots were discussed with quantitative calculations.     

Effect of annealing treatments on the microwave electromagnetic properties of amorphous FeCuNbSiB microwires

The amorphous FeCuNbSiB microwires are fabricated by using the melt extraction method and annealed separately at temperatures T = 573, 673, 723 and 773K for 1h. The effect of annealing treatment on the microwave electromagnetic properties of FeCuNbSiB wires/wax composites has been investigated for the first time. It is found that in a frequency range of 0.5--4.0GHz, the complex permittivity, permeability, magnetic and electric loss tangents of FeCuNbSiB wires/wax composites are strongly dependent on the annealing temperature and frequency. For T = 573, 723 and 773K, two resonance peaks are found at frequency f = 1.2 and 3.3GHz. However, for T = 673K, only one resonance peak occurs at f = 3.3GHz. The resonance peak at f = 1.2GHz is believed to be due to the stress-induced anisotropy, while the resonance peak at f = 3.3GHz is attributed to the random anisotropy.     

AlN/Si(100)上CVD SiC薄膜的光致发光谱

本工作用化学气相淀积方法在AlN/Si(100)复合衬底上生长SiC薄膜.外延生长过程中,采用C4H4和SiH4作为反应气源,H2作为载气.样品的X-射线衍射谱和拉曼散射谱显示,所得到的外延层为六角对称的SiC薄膜.俄歇电子能谱及X-射线光电子能谱的测量结果表明,在外延膜中存在来自衬底的Al和N元素.样品的光致发光测量显示,所有的样品均可在室温下观察到位于3.03eV和3.17eV处的发光峰,这分别相应于4H-SiC能带中电子从导带到Al受主能级之间的辐射跃迁和电子从N施主能级到价带之间的辐射跃迁,从而表明所得的外延薄膜的多形体为4H-SiC.