Thin films of In As and InSb directly evaporated on to substrates, such as glass, ceramics or ferrite, have interesting properties which make them suitable for galvanomagnetic devices as Hall probes or magneto resistors. The reasons for this are as follows: the Hall-sensitivity increases with decreasing thickness of the semiconducting layer. The higher inner resistance of thin films facilitates matching of the device to a particular circuit. Directly evaporated layers have a better heat dissipation factor than thin slices cemented to a substrate.Suitable methods of producing stoichiometric thin films of InAs and InSb with mobilities comparable to bulk material values are the flash-evaporation techniques and the three-temperature method. As the mobility shows a strong dependance on the crystallite size of the polycrystalline films, recrystallization techniques were subsequently applied to InSb films. This treatment results in larger crystallite sizes and mobilities of up to 30,000–40,000 cm2/Vs.The properties of thin film devices are discussed with special regard to Hall probes. The average values of mobility and Hall coefficient versus temperature and the resulting characteristics such as Hall-sensitivity, inner resistance, control current and temperature coefficient, are discussed with reference to several typical devices.