高速850nm VCSEL的研制

发布时间：2018-12-11 09:36

【摘要】：VCSEL具有高的调制速率,易于高速通信、圆形光斑易与光纤耦合、在光纤中传输时损耗低、高温度稳定性,减少在一定温度下正常工作需要调节器件所需合适参数带来的成本、低阈值电流和高效率,利于低功耗、易于二维集成、工艺成熟可靠、易于与其它光电器件集成等优势,一直得到了深入研究。随着大数据时代对建立高带宽、低功耗的绿色数据通信需求的日益增强,使高速VCSEL越来越成为最主流的高速光源之一,因此需要深入研究VCSEL的高速调制机理及限制高速调制特性的主要影响因素,解决传输速率和功耗的矛盾,使高速VCSEL成为高速光通信、光互联等光网络中的光源之一。本论文面向高速光通信,以研制-3d B带宽大于10GHz的VCSEL为目标,理论上深入研究850nm VCSEL的高速调制特性机理及限制因素,主要包括弛豫振荡频率、热、寄生RC参数及电极结构的微波反射特性等,并在实验上制备出-3d B带宽大于10GHz的VCSEL,最后对制备的VCSEL进行了分析静态特性和动态特性的研究和优化,实验结果与理论分析、软件仿真一致。本论文主要研究内容及结论概括如下:1.理论研究发现限制氧化限制VCSEL高速调制特性的主要因素主要包括:弛豫振荡频率、阻尼和寄生RC电路。弛豫振荡频率是VCSEL高速调制特性的最主要因素;通过对弛豫震荡频率的推导,理论研究发现限制弛豫震荡频率的主要限制因素是量子阱微分增益和光子寿命;研究VCSEL器件的寄生RC并建立器件的寄生电路模型,并利用二端口网络理论研究寄生电路的高频响应特性和电极结构的微波反射特性。2.研究制备高速VCSEL的关键工艺:湿法腐蚀、Al Ga As的湿氮氧化及BCB的刻蚀。Al Ga As材料在湿法腐蚀和湿氮氧化过程中的各向异性是导致氧化孔径呈现眼型的原因,但是对本实验制备的VCSEL中寄生RC参数的影响不大。研究了BCB在刻蚀过程中出现难以刻蚀并绝缘的玻璃状残留物的原因。3.制备了四种台面尺寸的单台面异面电极结构的VCSEL,对器件进行静态特性的研究,并重点研究VCSEL的动态特性。制备的VCSEL的-3d B带宽大于10GHz,约等于12GHz,并且带宽的测试受到了实验仪器测试带宽的限制;研究发现VCSEL的-3d B带宽随着驱动电流的增大呈现先增大后减小的趋势,主要是由于量子阱中载流子的泄露随着热的增大而增大,使微分增益减小导致的。实验结果与理论分析和软件模拟一致。4.利用二端口网络研究异面电极结构的反射特性及其对VCSEL高速调制特性测试的影响。研究异面电极结构的特征阻抗与电极结构参数的关系。实验制备的VCSEL的异面电极结构的反射系数为22%,并发现增大信号线的宽度同时减小片子厚度,可实现阻抗匹配。在片子厚度为100μm,信号线宽度为70μm时,特征阻抗为~50Ω。并进一步设计了易于工艺实现的特征阻抗匹配的同面电极结构,并研究了特征阻抗与同面电极结构相关参数的关系,发现对该电极结构的特征阻抗影响最大的是BCB的厚度、电极的宽度,且要求正负电极线之间的宽度大于30μm;5.对VCSEL进行RC参数的提取,并建立了器件的等效电路:其-3d B带宽大于10GHz。
[Abstract]:The vcsel has a high modulation rate, is easy to be high-speed communication, the circular light spot is easy to be coupled with the optical fiber, and has the advantages of being beneficial to low power consumption, easy two-dimensional integration, mature and reliable process, easy integration with other photoelectric devices and the like, and has been deeply researched. With the increasing demand of high-bandwidth and low-power-consumption green data communication in the large data era, the high-speed VCSEL is becoming one of the most mainstream high-speed light sources, so it is necessary to study the high-speed modulation mechanism of the VCSEL and the main influencing factors to limit the high-speed modulation characteristics. the contradiction between the transmission rate and the power consumption is solved, and the high-speed VCSEL is one of the light sources in the optical network such as high-speed optical communication and optical interconnection. This paper is aimed at high-speed optical communication. In order to develop the VCSELs with a bandwidth of more than 10GHz, the high-speed modulation characteristics and the limiting factors of the 850nm VCSEL are studied theoretically, including the relaxation oscillation frequency, the heat, the parasitic RC parameters and the microwave reflection characteristics of the electrode structure. In this paper, a VCSEL with a bandwidth of greater than 10GHz is prepared on the experiment, and the research and optimization of the static and dynamic properties of the prepared VCSEL are carried out. The experimental results are consistent with the theoretical analysis and the software simulation. The main contents and conclusions of this thesis are as follows: 1. The main factors that limit the high-speed modulation of VCSELs include: the relaxation oscillation frequency, the damping and the parasitic RC circuit. The relaxation oscillation frequency is the most important factor of the high-speed VCSEL's high-speed modulation. By the derivation of the relaxation oscillation frequency, it is found that the main limiting factors for limiting the relaxation oscillation frequency are the differential gain and the photon life of the quantum well. the parasitic RC of a VCSEL device is studied and a parasitic circuit model of the device is established, and the high-frequency response characteristic of the parasitic circuit and the microwave reflection characteristic of the electrode structure are studied by using the two-port network theory. The key technologies for preparing high-speed VCSELs are: wet etching, wet-nitrogen oxidation of Al Ga As and etching of BCB. The anisotropy of the Al Ga As material in the process of wet etching and wet-nitrogen oxidation is the cause of the presence of an eye-type in the oxide aperture, but the effect of the parasitic RC parameters in the VCSEL prepared in this experiment is not large. The reason of the glass-like residue which is difficult to etch and insulate during the etching process of BCB is studied. The VCSELs with four mesa-sized single-mesa heterohedral electrode structures were fabricated, and the static characteristics of the devices were studied, and the dynamic characteristics of the VCSELs were studied. the-3d b bandwidth of the prepared vcsel is greater than 10ghz, approximately 12ghz, and the test of the bandwidth is limited by the test bandwidth of the experimental apparatus; and it is found that the-3d b bandwidth of the vcsel tends to decrease as the drive current increases, mainly because the leakage of carriers in the quantum well is increased with the increase of the heat, and the differential gain is reduced. The experimental results are consistent with the theoretical analysis and the software simulation. The reflection characteristics of different surface electrode structures and its influence on the high-speed modulation characteristics of VCSEL are studied by two-port network. The relationship between the characteristic impedance and the parameter of the electrode structure is studied. The reflection coefficient of the heterohedral electrode structure of the VCSEL prepared by the experiment is 22%, and it is found that the width of the signal line is increased and the film thickness is reduced, and the impedance matching can be realized. The characteristic impedance was ~ 50 惟 when the film thickness was 100. m u.m and the width of the signal line was 70. m and the relationship between the characteristic impedance and the parameters related to the surface electrode structure is studied, the characteristic impedance of the electrode structure is found to be the largest, the thickness of the BCB, the width of the electrode, and the width of the positive and negative electrode lines is required to be greater than 30 mum; 5. The extraction of the RC parameters of the VCSEL is carried out, and the equivalent circuit of the device is established: its-3dB bandwidth is greater than 10GHz.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN248

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