We have studied the electrical properties of Si p-n junction diodes by deep level transient spectroscopy (DLTS) measurements. The p-n junctions were developed on a Phosphorus doped Si by depositing Al and annealing at various temperatures. In order to confirm junction formation, current-voltage and capacitance-voltage measurements were made. Two deep levels at Ec-0.17 eV (E1) and Ec-0.44 eV (E2) were observed in the DLTS spectrum. These traps have been characterized by their capture cross-section, activation energy level and trap density. On the basis of these parameters, level E1 can be assigned as V-O complex and E2 as P-V complex. These traps are related to the growth of n-Si wafer and not due to Al diffusion.