850nm面射型雷射之高速特性與等效電路萃取

Abstract

在本篇論文中，我們研究以平面製程製成的氧化侷限型(oxide-confined)垂直共振腔面射型雷射的高速特性，並使用質子植佈製程去降低氧化侷限型垂直共振腔面射型雷射的寄生電容。在經過質子植佈製程後，氧化侷限型垂直共振腔面射型雷射的小訊號調變頻寬可由2.3GHz提高到9GHz。而且經過質子植佈製程後，偏壓電流在6mA之氧化侷限型垂直共振腔面射型雷射有非常乾淨的10Gps眼圖及小於20ps的抖動(jitter)的6dB衰耗率(extinction ratio)。 為了研究氧化型垂直共振腔面射型雷射的本質調變頻寬限制，我們導入了一個等效電路來描述氧化型垂直共振腔面射型雷射的阻抗。我們根據這個等效電路模型來分析氧化侷限型與質子植佈氧化侷限型垂直共振腔面射型雷射間的寄生元件的變化。透過使用積體電路特性化及分析程式(IC-CAP) ，從量測資料中萃取出等效電路中每一個寄生元件值，找出垂直共振腔面射型雷射調變頻寬的限制因子。經由前述的分析萃取方法，我們發現由bondpad所產生的寄生電容的電容量可由在沒有經過質子植佈製程前的1.85pF降到在經過質子植佈的製程後的0.277pF。我們證明這種寄生元件值萃取的方法對於特性化垂直共振腔面射型雷射的高頻性能是非常有用的，且這種方法可以被應用於大部份以二極體為基礎構造的光電元件。

In this thesis, we investigate high speed performance of oxide-confined VCSELs with planar process and reduced parasitic capacitance by proton implantation. The parasitic capacitance of VCSELs was reduced using additional proton implantation. The small signal modulation bandwidth expanded from 2.3 GHz to 9 GHz after proton implantation. The eye diagram of VCSEL after proton implantation at 10Gps with 6mA bias and 6dB extinction ratio showed a very clean eye with a jitter of less than 20 ps. To investigate the extrinsic bandwidth limitation of the oxide VCSELs, an equivalent circuit for the VCSEL impedance was introduced. We analyze the difference of the parasitic components between the oxide-confined and oxide-implant VCSEL. The limitation factor of the modulation bandwidth can be found out through the extraction of each component value in the equivalent circuit by Integrated Circuit Characterization and Analysis Program (IC-CAP). The bondpad capacitance was found to reduce from 1.85 pF to 0.277 pF after proton implantation process. This extraction method was proved very useful to characterize the high speed performance of VCSELs and can be applied to most diode based optoelectronics devices.