Abstract: A spot on a layer of a 2D semiconductor material deposited on a substrate is irradiated so as to generate excitons, so that photons are emitted from the layer. The photoluminescence spectrum is recorded for different values of the charge carrier concentration in the layer. The modulation of the charge carrier concentration may be realized by modulating the output power of the light source used to irradiate the sample. The relation is recorded between the ratio of the photoluminescence intensity of a first peak in the spectrum related to radiative recombination from indirect bandgaps to the intensity of a second peak in the spectrum related to radiative recombination from direct bandgaps, and the carrier concentration. This relation is fitted to a model of the ratio that takes into account multiple recombination mechanisms, radiative and non-radiative. From this process, the trap density within the bandgap is derived.

Abstract: A method and apparatus are provided for a spectroscopic measurement for determining a lateral recess depth in the sidewall of a microstructure. The structure is formed on a larger substrate with the sidewall in an upright position relative to the substrate, and the recess extends essentially parallel to the substrate. The recess may be an etch depth obtained by etching a first layer relative to two adjacent layers, the layers oriented parallel to the substrate, the etch process progressing inward from the sidewall. An incident energy beam falling on the structure generates a spectroscopic response captured and processed respectively by a detector and a processing unit. The response comprises one or more peaks related to the material or materials of the substrate and the structure. According to the method, a parameter is derived from said one or more peaks, that is representative of the lateral recess depth.

Abstract: A spot on a layer of a 2D semiconductor material deposited on a substrate is irradiated so as to generate excitons, so that photons are emitted from the layer. The photoluminescence spectrum is recorded for different values of the charge carrier concentration in the layer. The modulation of the charge carrier concentration may be realized by modulating the output power of the light source used to irradiate the sample. The relation is recorded between the ratio of the photoluminescence intensity of a first peak in the spectrum related to radiative recombination from indirect bandgaps to the intensity of a second peak in the spectrum related to radiative recombination from direct bandgaps, and the carrier concentration. This relation is fitted to a model of the ratio that takes into account multiple recombination mechanisms, radiative and non-radiative. From this process, the trap density within the bandgap is derived.