Fabrication of Advanced Semiconductor Lasers and Other Optoelectronic Devices Using Focused Ion Beam Technology.

The progress made in recent years in the design and processing of semiconductor DBR/DFB lasers and waveguides has resulted in a surge in the development of optoelectronic integrated circuits (OEIC). Conventional technologies that employ lithography and etching suffer from complication and unreliability for OEIC fabrication. In this dissertation, an alternative approach using FIB compositional mixing technology is investigated. The mixing mechanisms were studied using a short period Al_{0.3}Ga _{0.7}As/GaAs superlattice structure. The effects of ion energy, dose, and RTA conditions on the FIB-induced mixing were characterized by various techniques. In the implanted region, the inter-diffusion process causing compositional mixing was significantly enhanced by the Si implantation. An ion dose as low as 1 times 10^{14}/cm ^2 results in a two-order of magnitude increase in the inter-diffusion coefficient. A further enhanced mixing ("pinch-off mixing") was observed at certain depth. The depth-dependent mixing is attributed to vacancy injection. A theoretical model was developed based on the experimental results. For the first time, the fabrication of DBR lasers and channel waveguides using FIB mixing technology was demonstrated. Third order DBR lasers as well as channel waveguides were fabricated by the single-step, maskless FIB mixing. Lasing operation was examined by optical pumping. With a pumping power 1.6 times above the threshold value, lasing modes were observed at a wavelength near 827 nm, with spacing of 3 A and a linewidth of 1.5 A. The maximum reflectivity of DBR was estimated to be {~} 94% while a grating coupling coefficient of {~}55.6 cm^{ -1} was computed. Channel waveguide loss of 17.2 dB/cm was measured compared to 10-12 dB/cm measured for planar waveguiding. The successful implementation of DBR lasers and channel waveguides has shown promising potential for the FIB compositional mixing technology in OEIC applications.