NOVELTY - A photosensitive device comprises: a silicon substrate (40) having several trenches on a surface, where the trenches are positioned to define at least one silicon fin (42); and stressed material within at least two of the trenches, where the stressed material induces strain within the silicon fin to reduce the band gap of at least a portion of the silicon within the silicon fin.    USE - As photosensitive device selected from a silicon solar cell, an image sensor cell, an infra red photodetector (claimed), photodiodes, avalanche photodiodes, and image sensing devices such as charge coupled devices (CCD) and complimentary metal-oxide-semiconductor (CMOS) image sensors used in camera applications.    ADVANTAGE - The photosensitive devices are made to include stressed silicon at or sufficiently near the junctions or other active regions of the devices to provide increased sensitivity to longer wavelength light. Stressed silicon has a lower band gap than conventional silicon. The reduced energy gap in strained silicon regions extends the range of sensitivity of a photo-sensitive silicon device to longer wavelengths of light corresponding to photon energies less than a fundamental energy band gap of bulk unstrained silicon. The reduction in band gap causes an increase in the absorption efficiency for longer wavelength (red) light which is desirable in image sensing devices such as charge coupled devices (CCD) and complimentary metal-oxide-semiconductor (CMOS) image sensors used in camera applications. Because the fins are strained, the band gap of at least part of the silicon in the fins is less than the strain-free or equilibrium band gap of bulk silicon. As a result, photons with longer wavelengths will generate electron-hole pairs, increasing the efficiency of the device. These electron-hole pairs represent additional current beyond that which would have been generated in a cell without any strained material. The additional light energy thus captured will contribute to an improved overall efficiency of the device.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a process for making a photosensitive device, involving: providing a silicon substrate; forming a mask on the silicon substrate, where the mask has a mask pattern; etching into the silicon substrate according to the mask pattern to form trenches, pairs of trenches defining several silicon fins; inducing strain within at least a portion of at least two of the silicon fins; and forming electrodes to provide electrical connections to the photosensitive device, where the strain within the silicon fins reduces the band gap of the at least a portion of the silicon fins and increases the sensitivity of the photosensitive device for wavelengths of light corresponding to energies of light less than a band gap of bulk silicon.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a process for forming a silicon solar cell, photodetector or imaging device.    Silicon substrate (40)    Silicon fin (42)