NOVELTY - A solar cell device (200) comprises substrate (202); passivation layer (210) disposed on non-light-receiving surface of substrate and having openings (212), where layer has first sub-layer of aluminum oxide and second sub-layer of silicon nitride disposed on first sub-layer; back contact (206) disposed on passivation layer in grid-like pattern covering openings and having aluminum doped with Group III element; and local contacts (214) formed at interface of substrate and back contact, where local contacts has region heavily doped with Group III element and silicon-aluminum eutectic alloy.    USE - As solar cell device (claimed) for generating energy.    ADVANTAGE - The solar cells have reduced carrier recombination; and have eutectic local contacts and passivation layers which reduce recombination by facilitating formation of a back surface field (BSF). The solar cell device has a reduced contact resistance inside the contact openings. The back contact solar cells are advantageous compared to conventional silicon solar cells because back contact solar cells have a higher conversion efficiency due to reduced or eliminated contact obscuration losses (sunlight reflected from contact grid is unavailable to be converted into electricity). The BSF formed at contact sites in a solar cell substrate is advantageous since they create an electric field with the substrate that 'reflects' the minority carriers away from the contact sites, which can increase the likelihood of the current being collected and effectively reduce the back surface recombination velocity, thus improving a solar cell's short-circuit current and reducing electron-hole recombination losses. The BSF also provides for lower electrical resistance at the contact, thereby reducing the contact resistance. The solar cells exhibit increased efficiency and decreased cost. The increased efficiency and reduced cost is facilitated by a patterned back contact, which reduces the amount of paste required to manufacture a solar cell, and increases eutectic composition uniformity. The efficiency is further increased due to reduced contact resistance and reduction of recombination at the back surface of a solar cell which is facilitated by the heavily doped back surface field. The reduced contact resistance is promoted by using a boron-doped aluminum paste as the back surface contact. The heavily doped back surface field is achieved due to a higher solubility of boron in silicon than aluminum. Therefore, boron dopes the silicon more heavily than aluminum.    DETAILED DESCRIPTION - A solar cell device (200) comprises a substrate (202); a passivation layer (210) disposed on a non-light-receiving surface of the substrate, where the passivation layer has openings (212) formed through it, where the passivation layer comprises a first sub-layer of aluminum oxide, and a second sub-layer of silicon nitride disposed on the first sub-layer of aluminum oxide; a back contact (206) disposed on the passivation layer in a grid-like pattern covering the openings, where the back contact comprises aluminum doped with a Group III element; and local contacts (214) formed at an interface of the substrate and the back contact disposed within the openings, where the local contacts comprises a region heavily doped with the Group III element and a silicon-aluminum eutectic alloy formed adjacent to the heavily doped region. The region has an active doping concentration of about 1019 to about 1020 atoms per cm3. The back contact comprises about 0.1 wt.% to about 10 wt.% of boron, gallium or indium. The back contact covers less than or equal to 50% of the non-light-receiving surface. The first sub-layer of aluminum oxide has a thickness of greater than or equal to 20 nm, and the second sub-layer of silicon nitride has a thickness of about 20 nm to about 100 nm. An INDEPENDENT CLAIM is included for a method of forming solar cell, involving: disposing a passivation layer on a non-light receiving surface of a substrate, where the passivation layer comprises a first sub-layer of aluminum oxide and a second sub-layer of silicon nitride disposed on the first sub-layer of aluminum oxide; forming openings through the passivation layer; disposing an aluminum paste over the passivation layer in a grid-like pattern covering the openings, where the aluminum paste comprises a Group III element; and heating the substrate and the aluminum paste disposed thereon to a temperature above a silicon-aluminum eutectic point; or providing a substrate having a front surface and a back surface, where the back surface is generally parallel and opposite to the front surface, the substrate has a first conductivity type; forming holes in the substrate, where the holes extends from the front surface to back surface; forming an emitter layer within the holes and on the front and back surfaces, where the emitter layer has a second conductivity type opposite to the first conductivity type; disposing an aluminum paste on the back surface of the substrate, where the aluminum paste comprises a Group III element; and heating the substrate and the aluminum paste disposed on it to a temperature above a silicon-aluminum eutectic point to form a region heavily doped with the Group III element in the substrate. The aluminum paste is doped with boron. The aluminum paste is disposed between the rows of the holes. The step of heating and cooling the substrate forms a region heavily doped with the Group III element in the substrate; or forms an aluminum-silicon eutectic composition within the openings of the passivation layer.    DESCRIPTION OF DRAWING(S) - The figure shows schematic sectional view of a solar cell.    Solar cell (200)    Substrate (202)    Front surface contact (204)    Back surface contact (206)    Doped region (208)    Passivation layer (210)    Contact openings (212)    Local contacts (214)