Abstract: Platinum Silicide (PtSi) layers formed on silicon substrates are well known for their ability to image in the infrared portion of the electromagnetic spectrum out to 5.75 micrometers. The detectors are formed on p-type silicon substrates of <100> orientation. This is the preferred crystal structure for silicon when used for fabrication of Very Large Scale Integration (VLSI). The cooling required for these devices is 77.degree. K., which is needed to reduce thermal currents in the diodes to be significantly below the infrared generated signal. Detector array operation at these temperatures does not allow for operation in space for extended missions because a closed cycle mechanical cooler must be used. We have developed a new PtSi detector which must be fabricated on p-type silicon having a <111> crystal orientation. The detectors have been measured for their cutoff wavelength and barrier height is 0.310 eV which translates to a cutoff wavelength of 4.0 micrometers.