深蝕刻布拉格反射鏡之邊射型微共振腔半導體雷射

Abstract

本論文以乾式蝕刻製作砷化銦鎵量子井與砷化銦量子點之深蝕刻布拉格反射鏡(DBR)邊射型半導體雷射，藉由DBR產生低損耗的微共振腔進而達到極低臨界電流操作的特性。首先利用砷化銦鎵量子井雷射做為測試，量測結果發現，布拉格反射鏡鏡面的確能降低臨界電流，證明了此製程之可行性。接下來我們做了三種不同鏡面組合雷射的分析比較，縮減其共振腔長度並且觀察元件特性隨溫度改變的差異。在量子井雷射的部分，我們最短的共振腔長度縮小至30µm，臨界電流為4.62mA。最小臨界電流則發生於共振腔長度50µm，為4.27mA。然而利用傳統方式萃取出的DBR反射率R不如預期精準，故必須引入損耗因子S才能萃取出更精確的反射率。此外，我們更進一步利用砷化銦量子點取代量子井，首度成功的將DBR雷射應用於1.3µm波段，並將共振腔長度縮小至250µm，其臨界電流為51.07mA，而共振腔長度為500µm有最低臨界電流4.91mA。

We report the fabrication of InGaAs quantum wells and InAs quantum dots edge emitting laser diodes with deep-etched Distributed Bragg Reflectors (DBR), which were patterned by e-beam lithography and etched by inductivity coupled plasma. By using DBR, a low loss micro-cavity will be formed for the laser diode so that the threshold current (Ith) of lasers is lower than cleaved lasers. At first, lasers of InGaAs quantum well structure with patterned DBR were investigated. From the measurements, we found that Ith decreases comparing with conventional lasers. Then, we discuss the device characteristics of laser diodes with three different mirror combinations, various cavity lengths, and different temperatures. Lasing have been achieved from 30-µm-long and 10-µm-wide devices exhibiting Ith of 4.62mA. The minimum of Ith, 4.27mA, was obtained with a 50-µm cavity length. The DBR reflectivity extracted by conventional method is not accurate as we expected. Therefore, the loss factor should be considered to obtain more precise the DBR reflectivity. Furthermore, we have successfully fabricated 1.3µm InAs quantum dots DBR laser for the first time. For a 250-µm cavity length, Ith of this shortest-cavity laser is 51.07mA. The minimum of Ith at 4.91mA was observed from a 500-µm-cavity InAs quantum dot laser.