【作者】 赵勇；

【导师】 江晓清；

【作者基本信息】 浙江大学 ， 微电子学与固体电子学， 2011， 博士

【摘要】 光通信技术的高速发展对光电子器件的要求越来越高,半导体光电子集成技术是实现高性能、低成本的光电子器件的有效途径。目前光电子器件所采用的材料主要是Ⅲ-Ⅴ族材料及宽带隙Ⅲ-Ⅴ族氮化物如AlN. GaN和InN等。这些材料与广泛使用的硅技术无法兼容且制作成本很高,因而限制了它们的应用领域。硅基光子学(Silicon photonics)将硅技术及光电子集成技术相结合,使硅技术的应用从微电子领域扩展到光电子领域。这是值得深入研究的课题。硅材料虽然由于其结构上的对称性,不具备一阶电光效应(Pockles效应),但是可以通过载流子色散效应对其进行电光调制,且可以获得良好的调制效果。SOI材料的大折射率差的特性可以大大缩小器件的尺寸。而微电子制作工艺经过几十年的发展,最小线宽可以做到只有三四十纳米,能够很好的应用于硅基光子器件的制作。本论文对载流子色散效应型硅基光波导器件进行理论及实验上的研究,目的是探索利用CMOS工艺制作载流子色散型硅基光波导器件的可行性。本论文的主要创新和贡献在于：(1)结合SOI材料结构、pin电学结构和商业的CMOS工艺线的要求,设计了研制硅基光波导器件的可行工艺流程,并成功制作了基于载流子色散效应的硅基光波导器件。在国内,我们最先尝试采用商业的CMOS工艺线方式来制作载流子色散型硅基光波导器件。(2)在理论和实验上分析了基于载流子色散效应的马赫-曾德尔干涉仪(Mach-Zehnder-interferometer, MZI)型硅基光波导器件的特性。详细分析了pin结的重掺杂区位置对器件的吸收损耗、散热、消光比、速度等的影响。为消除自由载流子吸收对器件的影响,分析了一种动态调整分束比以提高器件消光比的方法,理论上可以将消光比提高到45 dB以上。(3)对硅光波导中1550 nm波段的光电流效应进行了实验研究。利用pin硅波导中存在较宽的雪崩加速区域,观测到明显的雪崩放大电流,实验得到了接近于5的倍增因子。根据反偏pn结硅波导的光场与耗尽区的交迭特性和强电场作用下的隧穿效应,解释了在1550 nm波段pn结硅波导中光电流的增强,讨论了光生载流子对基于pn-MZI结构的硅光调制器的影响和消除方法。更多还原

【Abstract】 Optical communication advances so fast that higher and higher performance optoelectronic devices are demanded. High performance and low cost optoelectronic devices can be effectively implemented by utilizing semiconductor integration technology. The primary optoelectronic materials include III-V compounds and wide band gapⅢ-Ⅴnitride such as AIN, GaN and InN. However, the application areas of these materials are limited due to their incompatibility with silicon material and high fabrication costs. Silicon photonics, which combines the silicon technology with the integrated optoelectronic technology and makes the silicon technology be applied from microelectronics to optoelectronics, is worthy of intensive investigation.It is well known that silicon exhibits no linear electro-optic (Pockels) effect because of its centrosymmetric crystal structure. However, efficient electro-optic modulation can be achieved by employing free carrier dispersion (FCD) effect. Additionnally, device size can greatly shrink due to the large difference of refractive index in silicon-on-insulator (SOI). Minimum line width of 30 or 40 nm can be fabricated by the microelectronic process, which has advanced for decades and can be well applied to the fabrication of silicon photonic devices. In this thesis, silicon optical waveguide device based on the FCD effect is theoreticly and experimentally investigated, to explore the feasibility of fabricating this kind of device by utilizing the CMOS process. This thesis makes innovative works mainly in the following three aspects:(1) The characteristic of SOI material, the electric structure of the pin diode and the requirements of the CMOS process are considered together to design feasible process flows. By using these process flows, silicon optical waveguide devices based on the FCD effect were successfully fabricated. In China, we are the first group to fabricate this kind of device by employing a commercial CMOS process.(2) pin-MZI based silicon optical waveguide devices are theoreticly and experimentally analyzed. Analysis shows that the heavily doping position can influence absorption loss, heat dissipation, extinction ratio (ER) and speed of the device. Moreover, a method to improve the ER is analyzed by adjusting dynamically the splitting coefficient. By employing this method, the ER can be improved to more than 45 dB in theory.(3) The photocurrent effect in silicon waveguides at 1550 nm wavelength is experimentally investigated. Obvious avalanche photocurrent due to the wide avalanche impacting region in the pin diode is measured, with multiplication factor of about 5. On the other hand, the enhancement of the photocurrent in the pn silicon waveguide is mainly attributed to (ⅰ) the overlap between the optical field and the depletion layer and (ⅱ) the strong electric field induced tunnelling effect. Finally, the influence of the photocarriers to a pn-MZI silicon optical modulator and methods to alleviate this influence are also discussed.更多还原