Due to its outstanding features, graphene has become a vital topic in nanotechnology applications such as optoelectronic devices, sensors, batteries, and biomedical applications. This study has been focused on examining a heavily doped semiconductor in order to fabricate Schottky junction solar cell, where p-type graphene with heavily doped n-type silicon (p-G/n(+)-Si) Schottky junction solar cell with a top-window structure and active area of 0.11 cm(2) has been fabricated using simple techniques without photolithography system. High-quality monolayer graphene sheet was synthesized by CVD method, while the back- and front-metal contacts were achieved by thermal evaporation system using Cr, Ag, and Au. The effect of thermal annealing to the transferred graphene sheet and the p-doping of graphene were also investigated. The results indicate that the annealing treatment has significantly reduced the PMMA residue in the graphene sheet by similar to 75% as well as reduction in the PMMA islands' height. On the other hand, doping graphene with GO dispersion showed an enhancement in both J(sc) = 3.65 mA /cm(2) and V-oc = 420 mV which is an indication of larger graphene's work function. The best obtained power conversion efficiency of this cell after annealing treatment and doping was found to be around 2.24%. The results also showed how it is challenging to deal with heavily doped semiconductor in order to make a Schottky junction between graphene and the semiconductor, where the Fill factor was decreased after each processing step.