| Monolithic growth of III-V materials on Si has been pursued for over two decades with a major objective of achieving the integration of III-V light emitters with Si CMOS device technology. The majority of the work done in this field has been focused on the growth of GaAs on Si. This research has resulted in only a few demonstrations of devices (lasers, detectors and transistors) due to growth issues such as lattice mismatch, anti-phase domains and thermal expansion coefficient mismatch resulting in very poor epitaxial quality. In this research, we report high quality, low-defect density growth of antimonides on silicon using an AlSb nucleation layer. Our approach to monolithic III-V growth on Si is fundamentally different from the previously reported work due to the unique growth mode of AlSb on Si compared to GaAs on Si. We utilize a very thin AlSb layer (100 A) nucleated on Si, which relieves almost the entire strain caused by the 13% lattice mismatch via a 2-D array of 90° misfit dislocations. These dislocations form at the III-V epi/Silicon interface and propagate within that plane and do not thread vertically into the material. This growth mode produces relaxed, very low defect-density material as indicated by x-ray diffraction, transmission electron microscopy and etch-pitch density measurements. We have fully characterized this growth mode, which extends to GaSb on GaAs and other highly mismatched systems, and we have also developed a theoretical model to support our experimental data. We will discuss modeling and epitaxy along with device demonstrations that includes a monolithic edge-emitting and a vertical cavity surface emitting laser (VCSELs) on a Silicon substrate operating under room-temperature and optically-pumped conditions. The laser characterization includes lasing spectra and light-in versus light-out curves. |
