Wafer-Fused Orientation-Patterned GaAs
AIR FORCE RESEARCH LAB HANSCOM AFB MA SENSORS DIRECTORATE/ELECTROMAGNETICS TECHNOLOGY DIV
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The fabrication of thick orientation-patterned GaAs OP-GaAs films is reported using a two-step process where an OP-GaAs template with the desired crystal domain pattern was prepared by wafer fusion bonding and then a thick film was grown over the template by low pressure hydride vapor phase epitaxy HVPE. The OP template was fabricated using molecular beam epitaxy MBE followed by thermocompression wafer fusion, substrate removal, and lithographic patterning. On-axis 100 GaAs substrates were utilized for fabricating the template. An approximately 350 micrometers thick OP-GaAs film was grown on the template at an average rate of 70 micrometershr by HVPE. The antiphase domain boundaries were observed to propagate vertically and with no defects visible by Nomarski microscopy in stain-etched cross sections. The optical loss at 2 micrometers wavelength over an 8 mm long OP-GaAs grating was measured to be no more than that of the semi-insulating GaAs substrate. This template fabrication process can provide more flexibility in arranging the orientation of the crystal domains compared to the Ge growth process and is scalable to quasi-phase-matching QPM devices operating from the IR to terahertz frequencies utilizing existing industrial foundries.