Patent ID: 7534631

Claim:
A reflectometry method for gathering meaningful reflectance data indicative of one or more characteristics of a substance being grown within a reaction chamber at the time of measurement, the reaction chamber being elongate and substantially tubular such that gaseous semiconductor precursor material may be caused to flow therethrough along a direction substantially parallel to a longitudinal axis of the chamber, the chamber having a polygonal cross-section along a direction parallel to said longitudinal axis, the cross-section having first and second vertices disposed on either side of the substance being grown therein, said method including the steps of: directing light of known characteristics from a light source into the reaction chamber through an aperture in the first vertex of the polygonal cross-section and towards the surface of the substance being grown therein, and collecting the light reflecting from said surface and exiting the chamber through an aperture in the second vertex of the polygonal cross-section using a detector whereat the received light is converted into electrical signals which are subsequently subjected to computer processing, wherein the angle of incidence of the light with the surface is acute.