High resolution 1.3 megapixel extended wavelength InGaAs

Extended wavelength InGaAs detectors grown on InP substrates have been generally used only in single element detectors and low resolution linear arrays. The extended wavelength InGaAs is no longer lattice matched to the InP substrate so it requires buffer layers to be used in the epitaxial growth process to accommodate the strain of the mismatched material. These detectors are generally front side illuminated with wire bonded pads. This work describes the results of extended wavelength InGaAs detector arrays that are backside illuminated which presents many more challenges, including imaging through the buffer layers as well as hybridization to Si Readout Integrated Circuits (ROICs). The buffer layers absorb shorter wavelength light making NIR response challenging. The arrays produced in this work are at high resolution, 1.3 megapixels on small pitch of 12 µm. The imagers have response from 700 nm to <2000 nm while imaging via backside illumination. New processing methodologies were developed to extend the short wavelength response to allow for NIR response by removing the substrate and most of the buffer layers from the structure after hybridization. This has produced material with quantum efficiencies <50% across most of its detection range during TEC cooled operation.