A transmission electron microscopy study of microstructural defects in proton implanted silicon

The microstructure of silicon on defect layer, a new type of silicon-on-insulator material using proton implantation and two-step annealing to obtain a high resistivity buried layer beneath the silicon surface, has been investigated by transmission electron microscopy. Implantation induced a heavily damaged region containing two types of extended defects involving hydrogen: {001} platelets and {111} platelets. During the first step annealing, gas bubbles and {111} precipitates formed. After the second step annealing, {111} precipitates disappeared, while the bubble microstructure still remained and a buried layer consisting of bubbles and dislocations between the bubbles was left. This study shows that the dislocations pinning the bubbles plays an important role in stabilizing the bubbles and in the formation of the defect insulating layer. (C) 1996 American Institute of Physics.

CHARACTERISTICS OF OXIDES FORMED FROM A SI0.5GE0.5

X-ray photoelectron spectroscopy (XPS) combined with Auger electron spectroscopy (AES) have been used to study the oxides from a Si0.5Ge0.5 alloy grown by molecular beam epitaxy (MBE). The oxidation was performed at 1000 degrees C wet atmosphere. The oxide consists of two layers: a mixed (Si,Ge)O-x layer near the surface and a pure SiOx layer underneath. Ge is rejected from the pure SiOx and piles up at the SiOx/SiGe interface. XPS analysis demonstrates that the chemical shifts of Si 2p and Ge 3d in the oxidized Si0.5Ge0.5 are significantly larger than those in SiO2 and GeO2 formed from pure Si and Ge crystals.

A STUDY OF THE COMPOSITION DISTRIBUTION AT THE TI/AL2O3 INTERFACE USING THE MCS(+)-SIMS TECHNIQUE

In this article, the MCs(+)-SIMS technique has been used to characterize Ti/Al2O3 metal/insulator interfaces. Our experiment shows that by detecting MCs(+) secondary ions, the matrix and interface effects are reduced, and good depth profiles have been obtained. The experimental result also shows that with the increase of the annealing temperature (RT, 300 degrees C, 600 degrees C, 850 degrees C), the interface gets broadened gradually, indicating diffusion and reaction take place at the interface, and the interface reaction is enhanced with the increase in annealing temperature. When the temperature increases, the AlCs+ signal forms two plateaus in the Ti layer, indicating Al from the decomposition of Al2O3 diffuses into the Ti layer and exists as two new forms (phases). Also, with the increase of the annealing temperature, oxygen diffuses into the Ti layer gradually, and makes the O signal in the Ti layer increase significantly in the 850 degrees C annealed sample.

4×4热光SOI波导开关阵列

设计并制作了阻塞型和完全无阻塞型4×4热光SOI(silicon-on-insulator)波导开关阵列.开关单元采用了多模干涉耦合器(MMI)-MZI(Mach-Zehnder intederometer)结构的2×2光开关.阻塞型光开关附加损耗为4.8～5.4 dB,串扰为-21.8 dB～-14.5 dB.完全无阻塞型光开关阵列附加损耗为6.6～9.6 dB,串扰为-25.8～-16.8 dB.两者的消光比都在17～25 dB内变化,开关单元功耗小于230 mW.器件的开关时间小于3μs.功耗和开关速度都明显优于SiO_2基和聚合物基的开关阵列.

亚微米尺度高速电光调制器的研究进展

基于SOI(silicon on insulator)材料的亚微米尺度电光调制器成为了研究Si光电子学的重点.评述了亚微米尺度下SOI脊型光波导实现单模条件、偏振无关、低耦合损耗的技术要求,分析并比较了几种基于不同光学结构和电学结构的电光调制器的原理和特性,讨论了达到高速电光调制的方式.

慢光在光子晶体弯折波导中的高透射传播

研究了慢光模式在SOI(silicon-on-insulator)材料光子晶体线缺陷弯折波导中的传输特性.通过优化波导弯折处的结构参数,慢光模式在光子晶体60°与120°弯折波导中的透射率提高10倍以上,归一化透射率分别达到80%和60%以上.为了进一步减慢光速,设计了新颖的高Q值耦合腔弯折波导结构,在归一化透射率达到75%的基础上,光波群速度低至c/170(c为真空光速).研究结果对于增强光子晶体的慢光效应,提高光子晶体慢光器件的微型化和集成化都有一定的积极意义.