Development of High-Performance 1550 nm GaInAsSb Unitraveling Carrier Photodiodes (Invited)

High-performance Unitraveling Carrier Photodiodes (UTC-PDs) play central roles in the generation of sub-mm-wave and THz signals and high-rate data optical data transmission. The key advantage of UTC-PDs is that using a p-type absorber eliminates the detriments associated with slow hole transport compared to conventional PIN PD designs. Since their demonstration, the bulk of R&D activities have focused on GaInAs/InP heterostructure designs and their optimization. The principal challenge with such structures is electron extraction from the GaInAs absorber to the n-type InP collector layer. In 2005, the first GaAsSb/InP UTC-PD was demonstrated by taking advantage of the staggered band alignment between a GaAsSb absorber and InP, enabling electron collection without blocking down to zero bias. Unfortunately, the lower electronic mobility in GaAsSb did not result in competitive bandwidths with respect to GaInAs-based UTC-PDs. However, simulation-based studies suggested Type-II UTC-PDs should present advantages under high optical excitation. We recently revisited the "Type-II" UTC-PD concept by using quaternary GaInAsSb absorber layers nearly lattice-matched to InP to successfully mitigate the transport limitations of GaAsSb, enabling extremely linear power performance at high output levels, wide bandwidth operation in large area devices, and near 300 Gb/s optical data transmission without electronic post-amplification in devices with a 64 μm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> area. The presentation will describe past and current work, and outline possible further activities.