Wafer bonding with low-temperature grown compound semiconductor materials for optoelectronic device application.

摘要

This work uses a novel approach to achieve wafer bonding technique for high-brightness light-emitting diode (HB-LED) application with low-temperature-grown compound semiconductor materials as the bonding agents. These low-temperature grown materials were grown by molecular beam epitaxy ∼100°C and were found that their microstructures can be changed to either amorphous or polycrystalline structures by adjusting the group V flux during growth. For amorphous (Ga,As) material, it could be recrystallized to form polycrystalline structure as low as 300°C. This recystallization process strongly suggests that the atoms have moved around during annealing. It is only natural to assume that the movements of atoms may enhance the interchange of the atoms across the bonding interface, and hence, two wafers will bond if the low-temperature grown material was utilized as a bonding agent.; Two main material system were studied in this thesis, including (Ga,As) and (Ga,P). Several techniques were used to calibrate the properties of as-grown materials and the bonded samples, such as transmission electron microcopy, light transmission measurement, current-voltage (I-V) measurement. From the data we obtained, we found the polycrystalline (Ga,As) and (Ga,P) are better materials for light transmission, which is a very important parameter for HB-LED devices. Moreover, the I-V characteristics of bonded samples indicate that the ohmic behavior can be achieved with polycrystalline materials with Ga-rich condition.; Finally, I developed two methods to transfer a GaAs-based device layer on a transparent GaP substrate (for emission wavelength longer than 560 nm), which involve multiple processing techniques. One approach also includes the regrowth step, which further indicates the bonded sample can further be processed at high temperatures.