Abhay Joshi and Shubhashish Datta
Discovery Semiconductors, Inc.
119 Silvia Street
Ewing, NJ 08628, USA
Tel: 609-434-1311, Fax: 609-434-1317
Broadband focal plane array sensors, operating in the 0.25 to 2.5 µm wavelength range, are an enabling technology for several imaging applications including atmospheric greenhouse gas monitoring. Currently, hyper-spectral imagers use separate image sensors for different spectral sub-bands, for example GaN for UV, Si for visible, and InGaAs for IR, thus requiring expensive component-level integration. Our approach is to manufacture a single image sensor with 0.25 to 2.5 µm spectral range using GaAs substrates, which are commercially available in diameters as large as 6 inches. The key challenges, namely achieving high UV efficiency, low dark current, and high speed operation, are addressed separately in a lattice-matched GaAs UV-to-Visible photodiode and a lattice-mismatched InGaAs NIR-to-SWIR photodiode. The method for monolithically combining the two structures into a single UV-to-SWIR photodiode / photodiode array is also presented.
* Proc. of SPIE Vol. 8385 838507-1