Highly visible response from large-area indium gallium arsenide detectors

Abstract

Vapor grown indium gallium arsenide (InGaAs) detectors are normally1 fabricated with an indium phosphide (InP) cap layer which passivates the InGaAs and is transparent to light of a wavelength beyond 920 nm. Shorter wavelengths are strongly absorbed by this cap, and only ~5% of visible light is transmitted through a 2-μm thick InP cap. Previous work2 with 0.1- and 0.5-mm diam mesa detectors has shown that the visible response of these devices can be improved by utilizing thin (<1-μm) InP caps which allow significant transmission of visible light. The present work3 demonstrates that vapor grown planar InGaAs detectors with 2-, 3-, and 5-mm diam active areas can be made with quantum efficiencies as high as 38% at 400 nm, 42% at 600 nm, 50% at 800 nm, and 70% at 1300 and 1550 nm. Such detectors are unique and for the first time provide a usable large area high QE single-element detector for the 400-1700-nm spectral range, suitable as a traceable laboratory standard.