Investigation of the Effects of Rapid Thermal Annealing on MBE Grown GaAsBi/GaAs Heterostructures for Optoelectronic Devices.

摘要

High efficiency optoelectronic devices rely on high quality materials making up the device structure. The scope of this thesis investigates the effectiveness of rapid thermal annealing (RTA) at improving the material quality of GaAsBi/GaAs heterostructures. During the fabrication of a device, the contacts of the device had the rapid thermal annealing process accomplished to produce ohmic contacts and this research explored if this annealing treatment degraded the quantum wells that made up the active region of a device. To investigate these effects, a system to measure the photoluminescence of the material system was constructed utilizing Fourier Transform Infrared Spectroscopy. The photoluminescence intensity of the grown heterostructures was measured before and after RTA to see if there was any gain in the luminescence of the heterostructures. Measured gain is attributed to the reduction in non-radiative defects within the GaAsBi/GaAs material system. For the annealing time of 60 seconds, it was shown that the photoluminescence intensity does increase to a maximum at the 500°C annealing temperature. The maximum gain in photoluminescence intensity was 2.2 times that of the non-annealed intensity at room temperature. Over this temperature the optical quality of the material system began to degrade. The structure of the quantum well remained well formed until an annealing temperature of 750°C at which point the quantum well was destroyed. X-ray diffraction measurements were also performed to investigate the structural effects of rapid thermal annealing on the heterostructures. The post growth rapid thermal annealing process was shown to moderately improve the photoluminescence of GaAsBi/GaAs heterostructures by increasing the peak intensity by 2.2 times. The structure of the heterostructures under investigation displayed structural stability up to 750°C, proving that the structural stability could be maintained during the device fabrication process.