Depositing Pd or Au on n-InP at cryogenic substrate temperatures has previously been found to significantly increase the barrier height of the resulting Schottky diode. Cross-sectional transmission electron microscopy (XTEM) has been performed on Pd/InP and Au/InP interfaces formed at room temperature (RT) and low temperature (LT) to determine the differences responsible for the change in barrier height. In the Pd case, a solid state amorphization which occurs at the interface upon RT metal deposition is nearly eliminated in as-deposited LT Pd/InP diodes. In the Au case, RT deposition results in the initial monolayers of Au entering the InP lattice, while no such effect was observed in the LT Au/InP diodes. It is clear that the LT deposition dramatically reduces the interaction between the metal and substrate, resulting in a greater barrier height. Enhanced barrier height Schottky diodes are crucial to the development of optical and electronic devices on InP. Preliminary results will be discussed on metalsemiconductor- metal (MSM) photodetectors and metal-semiconductor field-effect-transistors (MESFET's) fabricated using the LT process.