There is a growing need in industrial and scientific research applications for very wide dynamic range, high sensitivity imaging methods. To fill this need, an advanced back-illuminated avalanche photodiode (APD) design is presented based on crystallographically etched (100) epitaxial silicon on R-plane sapphire (SOS), enabling large single photon sensitive, solid-state focal plane arrays with very wide dynamic range. The design will enable reliable and low cost fabrication. When (100) silicon

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... s properly etched with KOH:IPA:H 2 O solution through a thermally grown oxide mask, square based pyramidal frustum or mesa arrays result with the four mesa sidewalls of the APD formed by (111) silicon planes that intersect the (100) planes at a crystallographic angle, φ c = 54.7°. The APD is fabricated in the silicon mesa. Very wide dynamic range operation at high quantum efficiencies exceeding 50% for 250 nm< λ<400 nm and exceeding 80% for 400 nm< λ<700 nm, is enabled by a carefully optimized p-type boron spatial impurity profile, fabricated by high temperature diffusion. Monte Carlo modeling confirms the majority of electron-hole pairs are photogenerated outside of the narrow device multiplication region, resulting in a very low APD excess noise factor. be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited. CCC code: 0277-786X/09/$18 http://dx.doi.org/10.1117/12.806272 functions to inhibit optical cross-talk by shielding adjacent detectors from stray photons generated during the avalanche process. SOS-APD arrays are indium bump-bonded to CMOS readout ICs to produce hybrid focal plane arrays (FPAs) as shown in Fig. 2 , which might be 1024x1024 pixels or larger. [2,3] The camera lens focal length and focal ratio maintain 100% sensitive-area-fill-factor over the full FPA active area by limiting the maximum incidence angle of the extreme rays shown in red in Fig. 2 , incident at the microlens edges of the pixel, located farthest from the camera optic axis at the corner of the FPA.