NOVELTY - Fabricating a silicon solar cell structure (100a) involves forming a silicon nitride anti-reflective (AR) layer (106) n+ layer (104) formed on topside of substrate (114); forming silicon nitride layer on substrate backside; forming silver contacts (110) on AR layer; firing contacts; removing the nitride layer; forming i-type amorphous silicon layer on backside of co-fired substrate; forming p-type amorphous silicon layer on silicon layer; forming a conducting oxide layer (112) on silicon layer and forming aluminum contacts (108) on oxide layer using a low temperature firing of substrate.    USE - For fabricating a silicon solar cell structure.    ADVANTAGE - The silicon solar cell has a fill factor (FF) of 0.75-0.85, an open circuit voltage (Voc) of 550-650 mV, and a short circuit current density (Jsc) of 28-36 mA/cm2. The co-firing temperature and time exposed to the temperature allow for the simultaneous formation of front silver (Ag) contacts and aluminum (Al) back-surface field. The co-firing steps result in the formation of a uniform back-surface field (BSF) (or p+ layer) on the back-side of the co-fired solar cell structure. The co-firing process results in the etching of the silicon nitride AR layer by the glass frit contained in the Ag contacts to form a contact with the n+-type emitter layer, which allows n+-type emitter layer of higher sheet resistance values to be used. The co-firing process produces a solar cell structure with unexpected characteristics such as, an increased defect passivation (in low quality silicon substrates), which results in increased Jsc, increased Voc, and increased FF. The co-firing process also results in a more uniform Al BSF and a decreased BSRV. The co-firing process drives the atomic hydrogen from the SiNx AR layer into the silicon underneath on the gallium doped p-silicon substrate to passivate the defects in it, thus producing an improved bulk minority carrier lifetime. Thus, 1 second firing of SiNx/Al enhances processing throughput, bulk lifetime, and cell efficiency without sacrificing the Al-BSF quality. The improved BSF results from fast ramp up rates, very short hold time at about 740 degrees C, and fast ramp down rates, thus producing improved bulk lifetime by enhancing the retention of hydrogen at defects. The silicon solar cell structure has a bulk lifetime of 100-100 mu seconds, a series resistance (Rs) of 0.5-1 Omega -m2, a shunt resistance of 1000-2000 k Omega , a junction leakage current density of 7-10 nA/cm2, and a back surface recombination velocity (BSRV) of 50-900 cm/second.    DETAILED DESCRIPTION - Fabricating a silicon solar cell structure (100a) involves providing a p-silicon substrate (114) having a top-side and a back-side; forming a n+ layer (104) on the top-side of the p-silicon substrate; forming a silicon nitride anti-reflective (SiNx AR) layer (106) on the top-side of the n+ layer; forming a silicon nitride layer on the backside of p-silicon; forming silver (Ag) contacts (110) on the AR layer using a screen-printing technique; firing the Ag contacts; removing the silicon nitride layer removal from the backside of p-silicon substrate; forming an i-type amorphous silicon layer on the back-side of the co-fired p-type silicon substrate, where the i-type amorphous silicon layer has a front-side and a back-side; forming a p-type amorphous silicon layer on the back-side of the i-type amorphous silicon substrate, where the p-type amorphous silicon layer has a front-side and a back-side; forming a transparent conducting oxide layer (112) on the back-side of the p-type amorphous silicon layer, where the transparent conducting oxide layer has a front-side and a back-side; forming aluminum (Al) contacts (108) on the backside of the transparent conducting oxide layer using a low temperature firing of the p-silicon substrate; and forming a two-step fired silicon solar cell structure, where the Ag contacts are in electrical communication with the n+ layer. The method further involves disposing a screened printed aluminum grid onto the backside of the transparent conducting oxide layer.    DESCRIPTION OF DRAWING(S) - The figure shows a cross-sectional view of a silicon solar cell structure.    Silicon solar cell structure (100a)    N-type emitting layer (104)    Silicon nitride anti-reflective layer (106)    Aluminum contacts (108)    Silver contacts (110)    Transparent conducting oxide layer (112)    P-silicon substrate. (114)