This paper describes the recent progress in the device performance of the uni-traveling-carrier photodiode (UTC-PD). The UTC-PD utilizes only electrons as the active carriers and this unique feature is the key to achieving excellent high-speed and high-output characteristics simultaneously. The achieved performance includes a record 3-dB bandwidth (f3dB) of 310 GHz, a high output current over 180 mA with an f3dB of 65 GHz, a high linearity of up to 80 mA, and a zero-bias operation with an f3dB of 230 GHz and an output peak current of 6.8 mA.