University of New Mexico (Albuquerque, NM) researchers have fabricated III-V laser diodes grown monolithically on an industry-standard CMOS-compatible silicon (Si) substrate in the (100) orientation operating under continuous-wave, room-temperature conditions. They have demonstrated optically pumped vertical-cavity surface-emitting lasers and edge-emitting lasers, as well as p-n junctions with the very low leakage currents needed to make diodes (see “Race heats up for the silicon laser,” www.laserfocusworld.com/articles/272150).
Several key epitaxial innovations enabled realization of this laser. Interfacial misfit-dislocation arrays from aluminum antimonide (AlSb) nucleation on Si enabled by an atomic self-assembly process yielded low defect densities in the materials without the need for thick metamorphic buffers. The III-antimonide material was grown in etched grooves in a Si substrate to facilitate domain annihilation. The success of this approach was also aided by a relatively close match of thermal-expansion coefficients between Si and AlSb and a relatively large mismatch of sizes between Si and Sb atoms. Furthermore, the entire growth process was realized at temperatures below 500°C, which is also compatible with CMOS processes. The device exhibited an operating wavelength of 2.14 mm and a highly multimode spectrum. Contact Diana Huffaker at [email protected].