Valence band structure of SiGe/Si quantum wells.

The detector array is based on a new type of high performance thermistor material. Very thin (nm) Si/SiGe multi-layers are grown epitaxially resulting in a single crystalline material with integrated valence barriers. A high barrier gives a large temperature coefficient of resistivity (TCR), and is achieved with a high content of Germanium,  a low doping level and a relatively wide well. The TCR can thereby be high (3.3 %/K) and simultaneously, the high quality crystalline material provides very low 1/f-noise characteristics. Advantageous for the fabrication process is the stability of the quantum well thermistor material, which e.g. allows standard metallization annealing temperatures. Of importance for a low cost production is also the use of a well controlled and uniform fabrication method.