Study of post-growth annealing and Ga coverage effects in low-density GaAs/AlGaAs quantum dots grown by modified droplet epitaxy

We present a detailed analysis of the Ga coverage and of the post-growth annealing effects on the optical properties of very-low-density self-assembled GaAs/AlGaAs quantum dots grown by modified droplet epitaxy. Through theoretical calculation of the QD electronic states, including thermally activated Al–Ga interdiffusion processes, we were able to relate our spectroscopic observations to QD structural properties.     

Kraftfeld- und CNDO-Rechnungen von Vanadium-N-chlorimid-trichlorid CINVCL3

Force field and CNDO calculations were performed on CINVCl₃. These results give some evidence for the large CINV bond angle and the short CIN distance. One can conclude that for the CIN bond a large contribution must be assumed.

     

二阶系统边值问题的正解

以关于非线性全连续算子的锥不动点定为工具,研究二阶系统边值问题,在不假定ｆ,ｇ单调的情况下,得出了上述问题存在正解的若干充分条件。     

Number-theoretic properties of certain CR mappings

We first prove a uniqueness result for certain group-invariant CR mappings to hyperquadrics. For cyclic groups these mappings lead to a collection of polynomials ƒ_p,q (with integer coefficients) in two variables; here p and q are positive integers. We use the uniqueness result to prove some surprising number-theoretic results about the ƒ_p,q, in particular, ƒ_p,q is congruent to x^P + y^P modulo (p) (for P ≥ 2) if and only if p is prime. We also determine recurrence relations for these polynomials for q ≤ 3 and determine a functional equation for a generating function. Finally, we discuss the invariant polynomials that arise for certain representations of dihedral groups to illustrate the non-Abelian case.     

e+e-湮没中轻夸克碎裂为粲介子的研究

研究了e+e-湮没中"初始"轻夸克和胶子劈裂产生的组合为介子(包括D-, D-s, 0)或*介子(包括D*-, D*-s, *0)的过程.发现尤其在s=MZ处,其产额相对较大,当限制或*的能量大于20GeV时,它和c夸克碎裂产物的不变质量谱在稍大于2M附近有一个峰,这是该过程区别于其它或*介子产生过程的显著特征.此过程产生的矢量介子基本上是纵向极化的,与实验上观测到的*介子的纵向极化一致.     

V形槽硅微通道冷却器研制

报道了V形槽硅微通道冷却器的结构和主要制作工艺,研制了冷却器样品.性能测试结果表明冷却器在供水压力为2×105Pa时,封装面热阻尼系数为 0.051 ℃·cm2/W,能够用于封装峰值功率密度达到1 kW/cm2、工作占空比大于10%的激光二极管面阵.其冷却能力与数值模拟结果较吻合,尚存在流量较小的问题,原因可能在于导流槽内存在较大的水头损失,同时与导流槽的结构有关.     

Study of effects of Mn in CdS nanocrystals

Mn²⁺-doped CdS nanocrystals have been synthesized by adopting an aqueous solution precipitation method. These nanocrystals have been studied using X-ray diffraction (XRD), X-ray fluorescence (XRF), optical absorbance, photoluminescence (PL), DC electrical conductivity measurements and positron annihilation lifetime spectroscopy (PALS). The system has been found to be in the hexagonal phase. PL spectra have been studied on most prominent exciton peaks within the wavelength range (586–731 nm). The emission intensity is found to increase on increasing Mn²⁺ ion concentration (0–5%). Electrical conductivity lies within 0.819×10⁻⁶ to 1.69×10⁻⁶ Ω⁻¹ m⁻¹ and the system shows power law dependence for n=3–3.77. The Cd vacancies concentration has been found to decrease on increasing Mn%.     

Effect of oxide thickness on the capacitance and conductance characteristics of MOS structures

In this work, the investigation of the interface states density and series resistance from capacitance–voltage (C–V) and conductance–voltage (G–V) characteristics in Au/SnO₂/n-Si (MOS) structures prepared at various SnO₂ layer thicknesses by spray deposition technique have been reported. It is fabricated five samples depending on deposition time. The thicknesses of SnO₂ films obtained from the measurement of the oxide capacitance in the strong accumulation region for MOS Schottky diodes are 37, 79, 274, 401, and 446 Å, for D1, D2, D3, D4, and D5 samples, respectively. The C–V and G–V measurements of Au/SnO₂/n-Si MOS structures are performed in the voltage range from −6 to +10 V and the frequency range from 500 Hz to 10 MHz at room temperature. It is observed that peaks in the forward C–V characteristics appeared because of the series resistance. It has been seen that the value of the series resistance R_s of samples D1 (47 Ω), D2 (64 Ω), D3 (98 Ω), D4 (151 Ω), and D5 (163 Ω) increases with increasing the oxide layer thickness. The interface state density D_it ranges from 2.40×10¹³ cm⁻² eV⁻¹ for D1 sample to 2.73×10¹² cm⁻² eV⁻¹ for D5 sample and increases with increasing the oxide layer thickness.