All-epitaxial Orientation-patterned III-V Semiconductors for Nonlinear Optics

Book excerpt: Applications such as airborne countermeasures, chemical spectroscopy, and imaging require high-power, compact, and tunable light sources in the infrared (IR) and terahertz (THz) spectral ranges. While laser sources exist at certain frequencies in this range, they are bulky and require low temperature operation. An alternative solution is to generate the desired IR and THz frequencies through nonlinear optical frequency conversion in orientation-patterned III-V semiconductors using readily available, and room temperature operating high-power semiconductor lasers in the near-IR. Orientation-patterning is an all-epitaxial technique in which we fabricate quasi-phasematched semiconductor structures by the following steps: growth by molecular beam epitaxy (MBE), lithography, etching, and regrowth by MBE. Previous work on orientation-patterned GaAs has led to the demonstration of a variety of nonlinear optical devices; however, there is a push to develop orientation-patterned GaP (OP-GaP) to overcome inherent material limitations GaAs. This thesis work has been focused on the development of OP-GaP, including MBE growth and characterization of GaP films on Si and processing of OP-GaP structures. Improvements in material quality have been made through the course of studying the nucleation and growth conditions of GaP on Si to control the formation and annihilation of antiphase domain defects. Understanding the growth of GaP on Si has not only enabled the development of OP-GaP as a platform for nonlinear optical devices, but also enabled the initial investigation of III-V epitaxial mirrors on Si substrates for high performance optical coatings.