Work under this contract has focused on a field-assisted 1-2 micronsensitive photoemitter with a reverse biased Ge p-n junction and a thin Cs-O-activated emitting layer of negative electron affinity NEA GaAs. The p- GaAs provides an effective single-crystal low-work-function large-area biasing contact for the Ge p-n junction and allows the n-Ge to be sufficiently thin for optimal performance. Calculations show that some cooling, perhaps to -80 C, will be necessary to reduce the dark current well below the signal level. Detailed theoretical calculations are presented which show that 1-4 quantum efficiency in transmission is possible from either a GaAsGe or an InPGe device. The optimal design parameters are calculated, and the sensitivity of the parameters is discussed. GaAsGe growth using the metal chloride and organometallic vapor phase epitaxy OM-VPE methods has been studied in some detail. Only the OM-VPE process results in a true p-GaAsn-Ge heterojunction essential for our device. The metal chloride process suffers from Ge autodoping into the initial GaAs growth layer. Vacuum activation levels of thick GaAsGe have been very high in the reflection mode - comparable to homojunction GaAsGaAs activation levels. Ultra-thin diffused Ge junctions less than 1000 A deep have been successfully fabricated using the OM-VPE method.