Four samples of metal (n-type) semiconductor contact had been prepared as a form of Schottky
contact, Aluminum and Nickel metals and semiconductor substrate GaAs (donor) where used. The
Ohmic contact has been firstly made with thickness (500 nm) using Aluminum for two samples and
Nickel for other two, four samples were collected. These samples were annealed under the temperature of
(450 K) and pressure (10-4Torr) for (30 min.) to avoid the interfacial layers. Then Schottky contact where
made using Aluminum twice and Nickel twice with (120 nm) thickness and then we annealed the samples
under temperature (450 K) and pressure (10-4Torr) , the samples are as follows:(Al/GaAs/Al Ohmic,
Al/GaAs/Ni Ohmic, Ni/GaAs/Al Ohmic , Ni/GaAs/Ni Ohmic). The photocurrent as a function of
wavelength was calculated and it was found that the maximum value for the sample (Al/GaAs/Al
Ohmic) in the wavelength (800 nm), the dark current is (1.9 x 10-9Ampere). The detector coefficients of
the samples where calculated, the maximum Response at the wavelength (800 nm) was (0.157 Ampere/
Watt) and maximum Specific Directivity at the same wavelength is ( 63.7 x1011 Hz ½ Watt-1), the
maximum Noise Equivalent Power is (0.157 Watt Hz -½ ) and the maximum Efficiency is (24.4 %) at
the same wavelength, the photocurrent and Response values depended on the absorption coefficients
of metals and work functions the samples operated within the area under the near- infrared .