Abstract: In a process for determining the layer thickness of semiconductor layer structures, a sample of a multilayer semi-conductor (4) is placed in contact with an electrolyte (2) then subjected to anodic etching during which the depth of etching is determined by integration of the current. During etching, the sample (4) is also excited by an electric signal and the real component of the admittance and hence the conductance of the probe at the frequency of excitation is determined, the extreme values of this component are analyzed, and the values of the depth of etching corresponding to these extremes, which characterize the junctions between the layers of the sample (4) tested, are determined.

Abstract: A method for determining charged energy states of a sample of a semiconductor or insulator material by using deep level transient spectroscopy.

Abstract: A Deep Level Transient Spectroscopy (DLTS) method in which a high frequency measuring signal is applied continuously on a semiconductor junction, and exciting pulses are generated which are coupled through fast semiconductor switching elements to the junction to alternatively bias the junction in reverse and forward (or slightly reverse) directions. The high frequency measuring signal passed through the junction is evaluated by means of a lock-in amplifier phase-locked with a constant phase angle, independent of the repetition rate of the exciting pulses.The evaluation circuits of the apparatus including the lock-in amplifier are controlled by switching elements driven by control signals generated from the exciting pulses.

Abstract: A method and an apparatus for the differential thermal analysis of materials includes heating a first sample to be investigated and a reference sample by radiation heat transfer from respective separated radiation sources, controlling both sources according to a predetermined temperature program for the samples, interposing an element that partly transmits radiation between each of the samples and their associated sources, sensing the temperature difference between the elements, controlling one of the radiation sources in response to the temperature difference to equalize the temperature of the elements and measuring the temperature difference between the samples during the temperature program.