湿法腐蚀和干法刻蚀工艺对850 nmVCSEL高速调制性能的影响

Impact of Wet Etching and Dry Etching on Performance of High-speed 850 nm Vertical Cavity Surface Emitting Lasers

摘要:

垂直腔面发射激光器(VCSEL)以其低功耗、低阈值电流、高调制速率和易制作二维阵列器件等特点, 广泛应用于短距离光互连领域。湿法腐蚀和干法刻蚀作为高速VCSEL台面结构制备的两种工艺, 影响VCSEL氧化层的大小。文章研究了氧化层面积对寄生电容的影响, 并计算得到7 μm氧化孔径下采用干法刻蚀工艺的垂直腔面发射激光器, 相比较湿法腐蚀工艺, 氧化层电容由902.23 fF减小至581.32 fF, 谐振腔电容由320.72 fF减小至206.65 fF。通过对采用湿法腐蚀和干法刻蚀工艺制备的GaAs量子阱结构高速VCSEL进行小信号调制响应测试, 结果表明, 7 μm氧化孔径下干法刻蚀VCSEL小信号调制带宽提高至16.1 GHz。

Abstract:

Vertical-cavity surface-emitting lasers (VCSEL) are widely used in short-reach optical communication links and interconnects because of their low energy consumption, low threshold current, and high modulation speed. Wet etching and dry etching are two processes for high-speed VCSEL fabrication of mesa structure, which will influence the size of oxide layer. In this paper, the impact of the oxide layer on the parasitic capacitance is analyzed. Compared to the wet etching process, the oxide capacitance of 7 μm oxidized aperture VCSEL is reduced from 902.23 fF to 581.32 fF, and the capacitance associated with the intrinsic region is also reduced from 320.72 fF to 206.65 fF. The small-signal modulation response of high-speed VCSEL with GaAs quantum wells fabricated by wet and dry etching process were measured respectively, and the bandwidth of 7 μm oxide aperture VCSEL with dry etching was increased to 16.1 GHz.