High Efficiency Optical Detection at 1300nm to 1500nm on GaAs Substrates Using Pseudomorphic InGaAs

Pseudomorphic InGaAs with high InAs concentrations on GaAs substrates are currently in use in complementary-heterostructure FET (C-HFET) digital and MODFET MMW circuits. While their bandgaps enable them to detect 1300 and 1550 nm light, the projected detection efficiency (responsivity) is very low due to the limited thicknesses sampled by normally incident light. This proposal is to study the feasibility of building efficient long wavelength detectors on SI GaAs substrates by using laterally incident light, guided through an underlying waveguide, with leaky or resonant modes interacting with the thin InGaAs near the surface. With appropriate design, the InGaAs can be made to function both as the FET active layer, and, the optical detection layer, with the FET gate metals used in Schottky photodetectors. Success would enable 1300 and 1550 nm fiber technologies to be available for digital optical interconnects and phased array antenna remoting, while fully leveraging integrated GaAs digital and MMW ICs. Phase I will build simple device structures to compare responsivities for lateral (guided) incidence against vertical (unguided) incidence. Phase II will build the full up receiver and demonstrate it in a suitable test bed.