Abstract: A method for determining the thermal donor concentration of a test sample made of a semiconductor material, includes providing a reference sample made of the same semiconductor material and having a known thermal donor concentration; measuring a photoluminescence signal of the reference sample for a photon energy comprised between 0.65 eV and 0.8 eV, the photoluminescence signal of the reference sample exhibiting an intensity peak in a photon energy range of 0.65 eV to 0.8 eV; determining, from the photoluminescence signal, an experimental relationship between the thermal donor concentration and a parameter representative of the intensity peak; measuring a photoluminescence signal of the test sample for at least one photon energy comprised between 0.65 eV and 0.8 eV; determining from the photoluminescence signal a specific value of the parameter; and determining the thermal donor concentration from the specific value of the parameter by using the experimental relationship.

Abstract: Holder especially for a chuck key for a drilling or other machine tool, for which it is necessary to use a chuck key for opening and closing the chuck holding the working tools. The chuck key is attachable to the power cord of such a machine tool in such a way that it remains rotatable although not removable from the machine tool. To achieve this there is provided a locking device (2) mounted on the shaft of the chuck key, which locking device is inserted in a mounting device, which is attached to the power cord.