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 AlxGa1-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.