InP-based material for optoelectronic integration and solar energy conversion

• Main Author: Shiu, Kuen-Ting
• Format: Dissertation
• Language: English
• Subjects: alternative energy; engineering, electronics and electrical
• ISBN: 1124230955; 9781124230955

The purpose of this thesis is to utilize InP-based materials to both process the lightwave signals with large scale photonic integrated circuits and harvest the solar power with cheap, high-efficiency thin-film type solar cells. In the first part of the thesis, the reconfigurable add-drop multiplexer (ROADM) is used as the demonstration target. Past ROADM technologies were limited to passive optical components. Here, we adopt an asymmetric twin waveguide (ATG) technology with multiple tapers to successfully couple the light between on-chip optical amplifier and on-chip p-i-n detector. Passive components such as optical switches, waveguides, and multiplexer/de-multiplexer are also successfully demonstrated with same InP material system. Finally, a ROADM circuit capable of performing channel add/drop was fabricated and characterized by monolithically integrating these individual optical components onto the same InP substrate.
The second part of the thesis work focuses on realizing high-efficiency, thin-film InP-based solar cells. First, the motivation for developing III-V thin-film solar cells is illustrated via a cost analysis. Multiple choices of fabrication processes of InP thin-film solar cell, such as direct epitaxy, cold-welding with substrate removal, and cold-welding with epitaxial lift-off (ELO) are then demonstrated. For the process of cold-welding with ELO, the solar cell performance is compatible to that of a bulk counterpart. This process enables the preservation of the original InP substrate for regrowth following the thin-film solar cell fabrication.