Patent ID: 6963402
Filing Date: 2005-11-08
Classification: B82Y,G01N

Abstract:
1. A method of determining physical characteristics of a semiconductor quantum confined structure, the method comprising the steps of: a) illuminating an area of a surface of a semiconductor material wherein the semiconductor material comprises one or more quantum confined structures with a wavelength tunable laser beam having a center wavelength nearby to at least one “critical point” in the optical response of a semiconductor quantum confined structure, with a wavelength tuning range of approximately 15 nm or greater, and using a focal spot size of 40 microns or less, wherein the laser beam is passed through an electro-optic phase modulator operating at or above 1 MHz frequency to achieve modulation of the polarization state of tunable laser beam prior to illuminating the quantum confined structure; b) recording the reflected alternating current light from the illumination of the quantum confined structure, wherein the alternating current light contains one of the photo-induced changes in the semiconductor optical response, known as the photoreflectance signal, and the difference in the linear reflectivity of the “s” and “p” components of polarization, known as the linear reflectance signal or both; c) repeating steps a) and b) across the tuning range of the laser source of step so as to collect wavelength information in the vicinity of critical points in the optical response of the semiconductor quantum confined structure; d) repeating steps a) and b) across the power range of the laser source so as to collect intensity information in the vicinity of critical points in the optical response of the semiconductor quantum confined structure; and e) using the information collected in steps c) and/or d) to detect physical characteristics of the quantum confined structure.