Monitoring Epitaxial Layer Growth

When making a structure like AlGaAs or SiGe by heteroexpitaxial growth techniques, it would be nice to know when one atomic layer is completed so that the next can be started. The quality of the device depends on accurate control of the thickness and purity of each layer. Currently, no way exists to detect both layer growth and atomic composition during expitaxial processing of electronic and optoelectronic materials. Our proposed method allows detection of layer growth and atomic composition and would give data complementary to RHEED (reflection high energy electron diffraction) which is commonly used to sense the completion of each epilayer (but gives no composition data). We will accomplish this in real time with no instrumental obstruction of the vapor fluxes to the growing film. In addition, we can perform our experiment at pressure of a few mTorr which allows monitoring and control of films grown by LPCVD (low pressure chemical vapor deposition).