Large-area high-speed InGaAs photodetectors

A novel InGaAs structure has been developed specifically for use in high-speed applications that require large active area diodes with greater than 3mm diameter size. The device design is based on a thick and fully depleted PIN structure. The intrinsic layer thickness is 2 to 4 times thicker than that of the conventional PIN detectors. Greater than 3-fold reduction in detector capacitance per unit area and the corresponding RC time constant has been demonstrated. Even with such significant speed enhancement, other diode performance characteristics such as dark current and breakdown voltage of these novel InGaAs PIN detectors remain comparable to those of the conventional structure. Front- and backside-illuminated InGaAs detectors are fabricated. Both show equally high-quality spectral response and spatial uniformity. Comprehensive electro-optical tests are performed and the data and analysis are presented. Temperature dependent performance characteristics are also reported. Well-behaved performance characteristics are observed from TE-cooled temperatures to elevated temperatures above ambient.