The results of the thermodynamic analysis of the system Ge-I2-H2-He was used as a guide in designing a germanium epitaxial reactor. The equipment incorporates an instantaneous demand HI generator and is free of lubricated joints and valves. Cleaning of the apparatus is effected by the use of liner tubes and the system operates semiautomatically. Vapor growth studies were conducted to determine the effects on the surface morphology of grown layers caused by substrate parameters such as crystal orientation, resistivity, and conductivity type. It was found that the latter two parameters did not affect surface morphology, but that small crystal misorientations off of surfaces had pronounced effects. Growth rates in the system were of the order of 0.7 μ/hr under the conditions used, and values of ND-NA of 1015 electrons/cm3 were obtained routinely using undoped sources. Mobilities for the deposits were in the 14,000 cm2/v sec range at liquid nitrogen temperature. © 1965, The Electrochemical Society, Inc. All rights reserved.