A Molecular Beam Epitaxy Growth Technique for Quality 1.5 - 2.5 Micrometers near Infrared Sensing Devices.

The objective of this Program is to develop long wavelength, lattice mismatched InGaAs PIN diode structures grown using Molecular Beam Epitaxy MBE. The overall goal is to generate structures sensitive to the entire near infrared 1.0 - 2.5 micrometers which take advantage of the uniformity inherent to MBE but with a buffer structure practical for commercialization. The activity during Phase I was centered on an intermediate alloy, In.74Ga.28As, with optical response out to 2.2 micrometers. By the end of Phase I, PIN diodes were fabricated using thin less than 3 micrometers, low-temperature linearly graded buffers LTLGB of InxGa1-xAs. The diodes had grown-in p-n junctions and InAlAs passivation caps. Shunt resistivities RoA 75 ohms sq cm, and peak quantum efficiencies 70 were observed at room temperature. RoA had a temperature dependence with a diode quality factor of n1 .2. These results were near-commercial in level and represent the first practical alternative to non-uniform vapor phase epitaxy VPE material. During Phase II, the conventional planar process zinc-diffused junctions through an InAsP cap will be adapted to accommodate the MBE InAlAs cap, the opaque InGaAs LTLGB will be replaced by a transparent InAlAs buffer to enable backside-illuminated devices, and the indium content of the active layer will be increased to 82 for a cutoff wavelength of 2.5 micrometers jg p.3.