β-Ga2O3 单晶NH3中氮化的研究

为了将β-Ga2O3单晶应用于作为外延生长优质GaN薄膜的衬底材料，本文对β-Ga2O3 (100)进行了氮化处理，并且主要讨论了氮化温度以及β-Ga2O3表面的粗糙程度对GaN形成的影响。我们发现，最理想的氮化温度在900oC。此时，在抛光的β-Ga2O3的表面上生成了一层具有六方结构并且有择优取向的GaN层。本文同时也对氮化的机理进行了讨论。

Demonstration of GaN/InGaN light emitting diodes on (100) beta-Ga2O3 substrates by metalorganic chemical vapour deposition

The growth and fabrication of GaN/InGaN multiple quantum well (MQW) light emitting diodes ( LEDs) on ( 100) beta-Ga2O3 single crystal substrates by metal-organic chemical vapour deposition (MOCVD) technique are reported. x-ray diffraction (XRD) theta-2 theta. scan spectroscopy is carried out on the GaN buffer layer grown on a ( 100) beta-Ga2O3 substrate. The spectrum presents several sharp peaks corresponding to the ( 100) beta-Ga2O3 and ( 004) GaN. High-quality ( 0002) GaN material is obtained. The emission characteristics of the GaN/InGaN MQW LED are measurement. The first green LED on beta-Ga2O3 with vertical current injection is demonstrated.

Tm:Y_2SiO_5晶体的生长和光谱性质研究

采用中频感应提拉法生长了高质量的Tm:Y2SiO5(Tm:YSO)晶体,测定了晶体的晶格常数和分凝系数.运用劳厄照相法确定了单斜晶系Tm:YSO晶体的三个偏振轴〈010〉,D1和D2,在室温下测量了三个偏振轴方向的吸收光谱、荧光光谱和荧光寿命,计算了晶体吸收峰的吸收线宽和吸收截面.研究发现,相对于其他两个偏振轴方向,D1方向在790 nm处出现较强的吸收峰,同时在2μm附近出现了一定强度的发射峰,D1方向的吸收截面较大,荧光寿命较长.Tm:YSO晶体适用于AlGaAs二极管抽运固体激光器,在2μm波段固体激光器的应用上将有很大的发展潜力.

Photorelease of Pyridyl Esters in Organometallic Ru(II) Arene Complexes

New Ru(II) arene complexes of formula [((6)-p-cym)Ru(N-N)(X)](2+) (where p-cym = para-cymene, N-N = 2,2'-bipyrimidine (bpm) or 2,2'-bipyridine (bpy) and X = m/p-COOMe-Py, 1-4) were synthesised and characterized, including the molecular structure of complexes [((6)-p-cym)Ru(bpy)(m-COOMe-Py)](2+) (3) and [((6)-p-cym)Ru(bpy)(p-COOMe-Py)](2+) (4) by single-crystal X-ray diffraction. Complexes 1-4 are stable in the dark in aqueous solution over 48 h and photolysis studies indicate that they can photodissociate the monodentate m/p-COOMe-Py ligands selectively with yields lower than 1%. DFT and TD-DFT calculations (B3LYP/LanL2DZ/6-31G**) performed on singlet and triplet states pinpoint a low-energy triplet state as the reactive state responsible for the selective dissociation of the monodentate pyridyl ligands.

Ramp oxide termination structure using high-k dielectrics for high voltage diamond Schottky diodes

The promising theoretical properties of diamond, together with the recent advances in producing high-quality single crystal diamond substrates, have increased the interest in using diamond in power electronic devices. This paper presents numerical and experimental off-state results for a diamond Schottky barrier diode (SBD), one of most studied unipolar devices in diamond. Finding a suitable termination structure is an essential step towards designing a high voltage diamond device. The ramp oxide structure shows very encouraging electronic performance when used to terminate diamond SBDs. High-k dielectrics are also considered in order to further improve the reliability and electrical performance of the structure. © 2007 Elsevier B.V. All rights reserved.

Thermoelastic dissipation in MEMS/NEMS flexural mode resonators.

Understanding the energy dissipation mechanisms in single-crystal silicon MEMS/NEMS resonators are particularly important to maximizing an important figure of merit relevant for miniature sensor and signal processing applications: the Quality factor (Q) of resonance. This paper discusses thermoelastic dissipation (TED) as the dominant internal-friction mechanism in flexural mode MEMS/NEMS resonators. Criteria for optimizing the geometrical design of flexural mode MEMS/NEMS resonators are theoretically established with a view towards minimizing the TED for single-crystal silicon MEMS/NEMS flexural mode resonators.