REAL-TIME CONTROL OF HGCDTE GROWTH BY ORGANOMETALLIC VAPOR-PHASE EPITAXY USING SPECTROSCOPIC ELLIPSOMETRY

The use of spectroscopic ellipsometry for monitoring the vapor phase e pitaxial growth of mercury cadmium telluride (Hg1-xCdxTe) in real-time is demonstrated. The ellipsometer is used to perform system identific ation of the chemical vapor deposition reactor used for the growth of CdTe and to measure the response of the reactor to different growth co nditions. The dynamic behavior of the reactor is also studied by evalu ating the gas transport delay. The optical constants of Hg1-xCdxTe are determined at the growth temperature for different compositions. In-s itu real-time composition control is performed during the growth of Hg 1-xCdxTe. The required target compositions are attained by the ellipso meter and appropriate corrections are also made by the controller when a noise input in the form of a temperature variation is introduced.