Patent ID: 7391507

Claim:
A method of determining physical properties of a semiconductor structure, the method comprising the steps of: a) illuminating an area of a surface of the semiconductor structure using an amplitude modulated pump laser beam, the pump beam containing at least one wavelength with energy greater than the smallest interband transition energy of a semiconductor material within the semiconductor structure, thereby inducing time periodic changes in the electronic charge density within the semiconductor structure such that the electric field within the semiconductor structure obtains a time periodic modulation, and wherein semiconductor material within the semiconductor structure is subject to a time periodic modulation of interband transition energies; b) illuminating a portion of said area of step a) with a separate probe laser beam, the probe beam containing at least one wavelength nearby an interband transition energy of a semiconductor material within the semiconductor structure, and suitable for recording the induced changes in semiconductor material optical response which occur nearby to interband transition energies; c) recording the reflected alternating current probe light from the illumination of the semiconductor structure, wherein the alternating current probe light contains the induced changes in the semiconductor material optical response, known as the photo-reflectance signal; and d) using the information collected in steps a), b), and c) to determine physical properties of the semiconductor structure.