Innovation and Partnerships Office

Epitaxial Germanium Temperature Sensor IB-1561A


A method of making a highly sensitive epitaxial germanium low temperature sensor that is superior in the method of production and performance than those currently available. The geometry and sensitivity of the sensor can be tuned to desired temperature ranges, and specifically can operate at cryogenic temperatures. The sensor can be manufactured uniformly and reproducibly in large quantities at relatively low cost in which large area arrays are possible. The applications of the sensors range from conventional low temperature thermometry and control in laboratory and industrial settings, to applications associated with infrared, x-ray, particle and plasma physics and spectroscopy.


The invention is a method for making an epitaxial germanium temperature sensor using a chemical vapor deposition process (CVD) to deposit an epitaxial germanium layer onto a substrate. The epitaxial germanium layer is doped during the vapor phase of the CVD process to allow the layer to be resistive. Doping concentration is selected so that at temperatures below about 4K, resistivity of the layer is due to the mechanism of hopping conduction of free carriers.

The substrate can be made from silicon, germanium, sapphire or diamond, and can be a variety of sizes. In this way, the sensor can be manufactured to meet various production requirements. The dopant of the epitaxial germanium layer can be arsenic, phosphorus, or antimony and provided in a concentration that makes the epitaxial germanium resistive.

STATUS: Issued U. S. Patent # 7,232,487 available at