Test system for studies about devices' behaviour at low temperature

The paper presents a test system based on a cryostat and a gas thermometer used for studies about materials and devices behavior at low temperature. The system's functioning principle is described, including the gas thermometer's equation and its correcting terms and also the calculus method for setting-up the device-holder's isotherms. Finally, a discussion on the system's performances and the characteristics of some devices (a PRT and a FET) at low temperatures are given.