基于DBR增强的850nm GaAs/AlGaAs单行载流子光电探测器

DBR-Enhanced 850nm GaAs/AlGaAs Uni-Traveling-Carrier Photodiode

摘要:

高速850nm GaAs/AlGaAs面入射型单行载流子光电探测器(PD)是短距离光链路中的重要器件,面临着带宽和响应度之间的相互矛盾。报道了一种基于分布布拉格反射器(DBR)增强的GaAs/AlGaAs单行载流子光电探测器(UTC-PD)。DBR由20个周期的高/低Al组分的AlxGa1-xAs三元合金组成,可以在830~870nm范围内形成大于0.9的反射。在AlGaAs DBR的增强下,将GaAs吸收层所需的厚度降低到1040nm,兼顾PD对光的吸收率和光生载流子的渡越时间。采用双台面、聚合物平面化、共面波导电极结构制作了UTC-PD器件。该器件在850nm波长、-2V偏压下具有19.26GHz的-3dB带宽和0.4926A/W的响应度。

Abstract:

GaAs/AlGaAs surface-illuminated uni-traveling carrier (UTC) photodiodes (PDs) are critical devices for short-range optical links. However, a conflict exists between bandwidth and responsiveness. We report a GaAs/AlGaAs UTC-PD enhanced by a distributed Bragg reflector (DBR) that consists of 20 cycles of high/low Al component AlxGa1-xAs and has a reflectance ＞0.9 in the wavelength range of 830~870nm. The thickness of the GaAs absorption layer is reduced to 1040nm, which compromises the light absorption of the PD and transit time of photogenerated electrons. The UTC-PD device is fabricated with a double-mesas structure, polymer planarization, and a coplanar waveguide electrode. The device has a -3dB bandwidth of 19.26GHz, a responsivity of 0.4926A/W at a wavelength of 850nm, and a bias of -2V.