Guardring-Free Planar AlInAs Avalanche Photodiodes for 2.5-Gb/s Receivers With High Sensitivity

We demonstrate a practical 2.5-Gb/s AlInAs avalanche photodiode (APD) and an AlInAs APD-based optical receiver with high sensitivity. The AlInAs APD has a simple guardring-free planar structure with high reliability. In addition to the inherent low excess noise of AlInAs, their simplicity and high yields are great advantages in production, even when contrasted with the planar InP APDs now on the market. The guardring-free AlInAs APDs achieve larger gain-bandwidth (GB) products and lower excess noise, with a maximum 3-dB bandwidth of 6.0 GHz and a GB product of typically 80 GHz, and have equal performance with InP APDs, which have a responsivity of 1.0 A/W and a multiplying dark current of 2.2 nA. An AlInAs APD-based 2.5-Gb/s optical receiver with a SiGe transimpedance amplifier has a sensitivity of -37.0 dBm at a bit-error rate of 10
^-10