The evaluation of the diffusion of dopant materials inside Germanium was 'achieved by measuring the sheet resistance of the samples. Heat treatments during the above periodes of time caused the increase in the sheet resistance from ( 7.1 Ω /square ) to ( 32 Ω /square To recognize the doping profiles and to measure the build-in potential of the junctions , Capacitance-Voltage characteristics were measured . This measurement confirms that our Germanium junctions are one side-abrupt junctions and the built-in potential increases from ( 0.1 volt) to ( 0.4 volt) during the increasing of annealing time . The rectification of our diodes was evaluated by measuring current-voltage characteristics . these haracteristics improved with annealing time . General characteristics of a photodiode such as responsivity, quantum efficiency, detectivity and rise time were measured . The increasing of annealing time decreases the responsivity and shifts its peaks from (1.44 µm ) to ( 1.55 µ/n ). The same behaviour was observed for quantum efficiency and the detectivity. The rise time was increased from ( 114.8 nsec ) to (152 nsec) as a result of decreasing the annealing times.