Monolithically integrated In_0.53Ga_0.47As/In_0.52Al_0.48As front-end photoreceivers realized by molecular beam epitaxy and regrowth techniques

The performance characteristics of a monolithically integrated front-end photoreceiver consisting of a photodiode and a FET amplifier are analyzed. The materials, device, and circuit requirements are evaluated in terms of the calculated bandwidth and noise performance. A vertical scheme of integration is initially used to realize a photoreceiver circuit on InP consisting of a InGaAs PIN diode, a InGaAs/InAlAs pseudomorphic MODFET, and passive circuits elements. The device structures are grown by single-step molecular beam epitaxy with an isolating layer in between. The microwave performance of 1-μm gate MODFETs in the circuit is characterized by f_t = 9 GHz, although identical discrete devices have f_t = 30-35 GHz. The degradation is due to additional parasitic capacitances. The bandwidth of the circuit is 2.1 GHz. MBE regrown interfaces were investigated after a variety of in-situ and ex-situ dry and wet etching and/or annealing steps. Deep traps, interface state densities and interface recombination velocities were characterized, and the performance of regrown photodiodes and MODFETs was studied. These studies indicate that the integration of an as-grown high-speed photodiode with a regrown MODFET will eliminate parasitic effects and produce larger bandwidths.