ACCURATE MULTIPLE-QUANTUM-WELL GROWTH USING REAL-TIME OPTICAL FLUX MONITORING

We report a real-time molecular beam epitaxy control system based on optical flux monitoring (OFM) that is capable of producing thin AlAs/GaAs layers of accurate thickness. We demonstrate the system's ability to detect and compensate for growth rate variations by growing AlAs/GaAs multi-quantum-well structures while deliberately ramping the GaAs growth rate to simulate a severe effusion cell instability. Results show that a sample grown under these conditions without OFM control (i.e., while using conventional timed shutter control) exhibited multiple photoluminescence peaks, indicating that its quantum wells differed in thickness, while a sample grown using OFM shutter control exhibited a single narrow peak, indicating that its quantum wells were nearly identical in width. Analysis of the OFM shutter control sample's photoluminescence linewidth shows that the resulting quantum-well thickness variation were less than 1%.