The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 15, 2013
Filed:
Jan. 31, 2011
Alvin Gabriel Stern, Newton, MA (US);
Alvin Gabriel Stern, Newton, MA (US);
Other;
Abstract
An advanced, very high transmittance, back-illuminated, silicon-on-sapphire wafer substrate design is presented for enabling high quantum efficiency and high resolution, silicon or silicon-germanium avalanche photodiode detector arrays. The wafer substrate incorporates a stacked antireflective bilayer between the sapphire and silicon layers, comprised of single crystal aluminum nitride (AlN) and non-stoichiometric, silicon rich, amorphous silicon nitride (a-SiN), that provides optimal refractive index matching between sapphire and silicon. A one quarter wavelength, magnesium fluoride (λ/4-MgF) antireflective layer deposited on the back surface of the thinned sapphire provides refractive index matching at the air-sapphire interface. Selecting a composition of x=0.62 for a-SiN, tunes an optimal refractive index for the layer. Selecting design thicknesses of 52 nm for single crystal AlN, 30 nm for a-SiN, and 120 nm for λ/4-MgFyields a back-illuminated optical transmittance T>50% for 250-300 nm, T>70% for 300-400 nm and T>90% for 400-1100 nm.