Reflectance is the fraction of incident electromagnetic power that is reflected at an interface. Measurement of this material property provides a handful of parameters such as temperature, growth rate, thickness, composition, etc. The equipment (SVTA) combines traditional pyrometry with specular reflectometry to provide a single instrument to monitor both substrate temperature and film thickness in real time.
It is a technique easy to implement and a very common in-situ metrology tool used in molecular beam epitaxy systems. It is of uttermost importance when dealing with semiconductors or heterostructures which are not properly analysed with a simple pyrometer. Hence the name of reflectance corrected pyrometry. Associated with reflection high energy electron diffraction (RHEED), ion gauges and mass spectrometry, reflectance can also provide the growth rate of the layers and assist in inferring the flux of the cells and the thickness of the grown material. Finally, the data can also be analysed to characterize the layer's composition.