Process Control for CdZnTe Alternative Substrates by MOCVD

Alternative growth substrates such as CdZnTe/GaAs/Si promise to reduce the manufacturing cost of today's advanced infrared focal plane arrays (IRFPAs). Current MOCVD growth processes operate in an uncontrolled mode and require frequent calibration runs to maintain reproducibility. This results in reduced yield and throughput and, therefore, increased costs. The goal of Phase I is to identify and demonstrate the feasibility of compatible sensor technologies which can provide in-situ monitoring and feedback control of wafer growth in the CdZnTe material system. We will implement two types of sensors: the first will measure the concentration of reactant sources in the gas phase. This data can be used to provide real-time control of film growth-rate and composition. The second is a wafer sensor which measures film thickness and composition during growth. An innovative, high-uniformity, single-wafer reaction chamber incorporating the control sensors will be designed for first-pass success of complex device structures. A breadboard demonstration of the key sensors will establish the feasibility of our proposed approach in Phase I. In Phase II, the reaction chamber will be built and real-time feedback control will be demonstrated. Anticipated Benefits/Potential Applications - Development of a feedback- controlled reactor will significantly advance the state of the art in MOCVD materials growth. Feedback-controlled reactors will be attractive to manufacturers of multi-layer III-V and II- VI devices such as photodiodes, laser diodes, HBTS, and solar cells. Additionally, the ability to produce complex device structures at significantly improved yields will result in lower cost of commercial wafers.