New Materials and Methods for Tunable Mid-Infrared Laser Fabrication

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9802396 McCann This project covers the growth, characterization, and processing of IV-VI semiconductor layers grown by both liquid phase epitaxy (LPE) and molecular beam epitaxy (MBE) on silicon substrates to provide the materials science basis for improvements in mid-IR lasers. Owing to a large band gap dependence on temperature, lasers made from IV-VI semiconductors have tuning ranges of several hundred wavenumbers in the mid-infrared region, 3 microns to over 20 microns, where most molecules have strong absorption bands. This tunability, an advantage over mid IR lasers based on quantum cascade technology, and the expected improvement in cw operating temperatures using lift-off fabrication methods make IV-VI semiconductors attractive materials for enhanced mid-IR laser performance. This research seeks fundamental understanding of strain relaxation in highly thermal expansion mismatched epitaxial layers, work that can lead to the integration of compound semiconductor devices on silicon substrates. It is also expected to lead to the development of a new materials technology that can dramatically improve maximum operating temperatures of mid-IR lasers. The project is co-supported by the DMR Electronic Materials Program and the EPSCoR program. %%% The project addresses basic research issues in a topical area of materials science having high potential technological relevance. The research will contribute basic materials science knowledge at a fundamental level to new aspects of electronic/photonic devices. The basic knowledge and understanding gained from the research is expected to contribute to improving the performance and stability of advanced devices by providing a fundamental understanding and a basis for designing and producing improved materials, and materials combinations. A direct benefit of this research is that it will enable the development of user friendly mid-IR laser spectrometers, instruments that can be used in a variety of applications includ ing air pollution monitoring, real-time process control, and medical diagnostics. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area. ***