Abstract: In an embodiment, a semiconductor structure includes a support substrate comprising a surface adapted to support epitaxial growth of a Group III nitride, one or more epitaxial Group III nitride layers arranged on the surface and supporting a plurality of transistor devices assembled upon the support substrate, and a test structure formed in a Group III nitride layer. The test structure includes a plurality of trenches configured to provide an optical diffraction grating when illuminated by UV light. The trenches have a parameter corresponding to a parameter of a feature of the transistor devices.

Abstract: In an embodiment, a semiconductor structure includes a support substrate comprising a surface adapted to support epitaxial growth of a Group III nitride, one or more epitaxial Group III nitride layers arranged on the surface and supporting a plurality of transistor devices assembled upon the support substrate, and a test structure formed in a Group III nitride layer. The test structure includes a plurality of trenches configured to provide an optical diffraction grating when illuminated by UV light. The trenches have a parameter corresponding to a parameter of a feature of the transistor devices.

Abstract: In an embodiment, a method for evaluating a surface of a semiconductor substrate includes directing an incident light beam having multiple wavelengths at a position of a layer having a surface profile configured to form an optical diffraction grating, the layer including a Group III nitride, detecting a reflected beam, reflected from the position, and obtaining a spectrum of reflected intensity as a function of wavelength, the spectrum being representative of the surface profile of the position of the layer from which the beam is reflected, comparing the spectrum obtained from the detected beam with one or more reference spectra stored in memory, and estimating at least one parameter of the surface profile.