For high performance operation of semiconductor lasers consisting of low-dimensional electron systems as the active medium, a good size uniformity and a formation of low-damage interfaces are essentially required. In this paper, we review our recent results obtained by GaInAsP/InP based long-wavelength lasers consisting of quantum-wire structures fabricated by electron beam lithography, CH4/H2-reactive ion etching and 2-step organo-metallic vapor-phase-epitaxial growth processes.
Good size uniformity of vertically-stacked multiple-quantum-wire structures was obtained with a standard deviation of less than ±2 nm. By using a strain-compensated quantum-well structure as an initial wafer, non-radiative recombinations at etched/regrown interfaces were fairly reduced, which resulted in a room-temperature continuous-wave (RT-CW) operation of a quantum-wire laser for more than 15,000 hours. By taking an advantage of this fabrication method, 1540 nm wavelength quantum-wire distributed feedback (DFB) lasers were also realized for the first time with relatively low threshold current and high differential quantum efficiency under a RT-CW condition.
Moreover, by utilizing the energy blue shift due to the lateral quantum confinement effect, a low threshold current operation with a stable single-mode property has been successfully demonstrated for distributed-reflector (DR) lasers consisting of a DFB section with wirelike active regions and a passive distributed-Bragg-reflector (DBR) section with narrow quantum-wire active regions.