| 摘要 |
The efficiency of photo diodes is according to a basic idea improved by using them upside-down through letting the light ( 20 ) enter via the substrate layer ( 1 ), and by using the surface layer ( 3 ) as a mirror. Then, the epitaxial layer ( 2 ) has an approximately doubled chance to convert photons to electron-hole-pairs: either during a first pass when coming from the substrate layer ( 1 ) or during a second pass after being reflected at the surface layer ( 3 ). The surface layer ( 3 ) comprises metal stripes ( 6,7,8 ) and metal mirrors ( 9,10 ) and comprises metal areas ( 15,16 ) coupled to solders bumps ( 4,5 ) for precisely mounting said photo detector on a flexible printed-circuit board. The epitaxial layer ( 2 ) and areas ( 17,18,19 ) in the epitaxial layer ( 2 ) form electrodes of a first diode, and the epitaxial layer ( 2 ) and the substrate layer ( 1 ) form electrodes of a second diode which approximately doubles said efficiency again when adding the photocurrents of both diodes. A substrate layer ( 1 ) comprising silicon-on-insulator and/or an etch stopper can be easily made thinner by removing the silicon and/or by etching until said etch stopper.
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