标题: | 850 nm 面射型雷射布拉格反射镜特性之模拟分析 Simulation and Analysis of Distributed Blagg Reflectors 850 nm VCSELs |
作者: | 柯力泰 KE , LI-TAI 杨赐麟 S. L. Yang 理学院应用科技学程 |
关键字: | 850nm氧化局限型结构;分布型布拉格反射镜;张力披覆层;850 nm oxide-confined vertical-cavity surface-emitting laser;DBR;tensile-strain cladding |
公开日期: | 2005 |
摘要: | 本论文利用ISE-TCAD已设计的850nm氧化局限型结构,模拟元件结构掺杂浓度最佳化条件,而得n型DBR的掺杂浓度为 = 2.5x1O18 cm-3; p型DBR的掺杂浓度为 = 1x1O19 cm-3是最适当的。或许制程上的进步我们可以再提高掺杂浓度,但因电子电洞移动率及所造成的材料电阻率的差异,须保有 > 的前提。 因考虑降低串联电阻、临界电流的问题,故设计了渐变式(graded) 披覆层与张力(tensile strain)披覆层。从元件的L-I-V特性表现可见,当张力披覆层厚度大于10 nm 时元件即无法雷射(Lasing),此应是量子穿隧效应的结果;而当张力披覆层厚度为3 nm 时,则有非常好的发光效率与临界电流,此可证明张力披覆层的功效。 最后,我们模拟分析各种状况的分布型布拉格反射镜(DBR)反射率。对于渐变式(graded) DBR而言,当中间层厚度为20 nm 以上时,DBR 就需要25对以上才能有与一般阶梯式DBR一样的反射率水准。若 DBR 各层厚度有+/- 1%误差度,只要有25对以上的DBR,其截 止带( stop band )宽度即够大,而在850 nm 处的反射率值也几乎不受影响。另外以矩阵光学为基础,我们进一步分析DBR对非正向入射光的反射率,在 45º 的入射角下,形成建设性干涉的光的波长约缩短约20 nm。 In this thesis work, we simulated and analyzed the optoelectronic properties of 850 nm oxide-confined vertical-cavity surface-emitting laser (VCSEL) diodes using ISE-TCAD simulation software. For the optimized characteristicsof VSCELs, n type DBR doping concentration = 2.5x1O18 cm-3 and p type DBR doping concentration = 1x1O19 cm-3 .Even thought we can increase the doping density in the advantage process, still need to follow > are expected. Considering the resistance and threshold current concerns of VCSELs, we simulated the graded and tensile strain cladding layers. Judging from the L-I-V characteristics, we found the fact that the thicker tensile-strain cladding layer greater than 10nm may prohibit the device from lasing. And the 3 nm-thick tensile-strain cladding layer can give low threshold currents and high lasing efficiency of VCSELs. Furthermore, we simulated the optical reflectance of various DBR structures. In the graded DBRs, when the thickness of the graded layers are over 20 nm, 25 pairs more DBR structures can give the same reflectance of regular abrupt DBRs. As the thickness of DBR layers are in 2% variation, processes, 25 pairs more DBR structure can also provide the same reflectance values of non-variant DBRs at the main wavelength and applicable stop-band width. Finally we utilized the matrix optics to analyze the effects of pair numbers and light incident angle on the reflectivity spectra of DBR. For the case of 45º incident angle of light ,the resonant wavelength shift about 20 nm. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#GT009377503 http://hdl.handle.net/11536/80319 |
显示于类别: | Thesis |