Recent Progress in Silicon Electro-optic Modulators for High Speed Applications

Silicon-based high-speed electro-optical modulator is the key component of silicon photonics for future communiction and interconnection systems. In this paper, introduced are the optical mudulation mechanisms in silicon, reviewed are some recent progresses in high-speed silicon modulators, and analyzed are advantages and shortages of the silicon modulators of different types.

一种CMOS折叠结构ADC中的失调抵消技术

CMOS折叠预放电路的失凋是限制CMOS折叠结构A／D转换器实现高分辨率应用的主要原因之一．文中提出差分对的动态匹配技术改善了折叠预放电路的失调，从而为研制CMOS工艺中的高分辨率折叠结构A／D转换器提供了一种可行方案，并给出了MATLAB和电路仿真的实验结果．

离子束外延β-FeSi_2/Si薄膜的电子能谱研究和表征

用电子能谱分析方法对低能离子束外延(IBE)生长的β-FeSi_2进行了详细研究，并对其电子能谱进行了表征。实测出XPS价带谱与有关理论计算结果相符，用XPS价带谱来表征β-FeSi_2比光电子峰更为清晰、可取。同时，对样品纵向分析表明界面处存在有较厚的过渡层。根据分析结果对低能IBE生长机理进行了探讨。经研究认为:Fe,Si通过空位机制进行的增强互扩散，在高温下生长出与Si晶格相匹配的β-FeSi_2。

Energy band and acceptor binding energy of GaN and AlxGa1-xN

The hole effective-mass Hamiltonian for the semiconductors of wurtzite structure is established, and the effective-mass parameters of GaN and AlxGa1-xN are given. Besides the asymmetry in the z and x, y directions, the linear term of the momentum operator in the Hamiltonian is essential in determining the valence band structure, which is different from that of the zinc-blende structure. The binding energies of acceptor states are calculated by solving strictly the effective-mass equations. The binding energies of donor and acceptor for wurtzite GaN are 20 and 131, 97 meV, respectively, which are inconsistent with the recent experimental results. It is proposed that there are two kinds of acceptors in wurtzite GaN. One kind is the general acceptor such as C, substituting N, which satisfies the effective-mass theory, and the other includes Mg, Zn, Cd etc., the binding energy of which deviates from that given by the effective-mass theory. Experimentally, wurtzite GaN was grown by the MBE method, and the PL spectra were measured. Three main peaks are assigned to the DA transitions from the two kinds of acceptor. Some of the transitions were identified as coming from the cubic phase of GaN, which appears randomly within the predominantly hexagonal material. The binding energy of acceptor in ALN is about 239, 158 meV, that in AlxGa1-xN alloys (x approximate to 0.2) is 147, 111 meV, close to that in GaN. (C) 2000 Published by Elsevier Science S.A. All rights reserved.