A multilayer stack of bonded GaAs wafers, each layer rotated 180° from the adjacent one, has been proposed for quasi‐phase‐matched second harmonic generation. Current bonding technology, however, often leads to unacceptable optical losses and, therefore, poor device performance. In this study, three sources of optical losses were investigated: (i) interfacial defects between the wafers, (ii) bulk defects within the wafers, and (iii) decomposition at the exposed outer surfaces. Surface losses due to incongruent evaporation were easily eliminated by repolishing the outer surfaces. However, to minimize the losses from interfacial and bulk defects, it was necessary to investigate the relationship between these defects and the processing parameters. It was found that an increase in temperature and/or time led to a decrease in interfacial defects, but an increase in bulk and surface defects. Optimized processing conditions were developed which permit the preparation of stacks containing over 50 layers of (100) GaAs wafers, and about 40 layers of (110) GaAs wafers. Optical losses as low as 0.1 to 0.3 % per interface (at 5.3 and 10.6 μm) were observed for the (110) oriented multilayer structures.
Source:IOPscience
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This paper presents the entire fabrication and processing steps necessary for wafer scale monolithic integration of series interconnected GaSb devices grown on semi-insulating GaAs substrates. A device array has been fabricated on complete 50 mm (2 inch) diameter wafer using standard photolithography, wet chemical selective etching, dielectric deposition and single-sided metallization. For proof of concept of the wafer-scale feasibility of this process, six large-area series interconnected GaSb p–n junction thermophotovoltaic cells with each cell consisting of 24 small-area devices have been fabricated and characterized for its electrical connectivity. The fabrication process presented in this paper can be used for optoelectronic and electronic device technologies based on GaSb and related antimonide based compound semiconductors.
Source:IOPscience
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send us email at sales@powerwaywafer.com and powerwaymaterial@gmail.com