Advanced InGaAs/InAlAs/InP avalanche photodiodes for high speed detection of 1.55 μm infrared radiation

High-speed, high-sensitivity, avalanche photodiodes operating at 1.55 mu m spectral range have been utilized in modern long-haul and high-bit rate optical communication systems. Related research was focused on developing detectors with minimized excess noise and maximized gain-bandwidth product. Recently imaging and critical sensing applications stimulated development of modified avalanche photodiode structures operating in 1.55 pm spectral range. For these devices speed is no more critical. Instead, very low current densities and low multiplication noise are the main requirement. In the present work the performance of uncooled InGaAs/InAlAs/InP avalanche photodiodes operating near 1.5 mu m has been studied. Device modeling based on advanced drift and diffusion model have been performed with commercial Crosslight APSYS simulator. Conventional separate absorption, charge and multiplication (SACM) avalanche photodiode as well as devices with a relatively thick undepleted p-type InGaAs absorption region and thin InAlAs multiplication layer have been considered. The latter type of APD structure enables to increase device quantum efficiency, reduce dark current and eliminate impact ionization processes within absorbing layer.