LOW-THRESHOLD QUANTUM-WELL ALGAAS HETEROLASERS FABRICATED BY LOW-TEMPERATURE LIQUID-PHASE EPITAXY AND EMITTING AT WAVELENGTHS 730-850-NM

An investigation was made of laser based on AlGaAs heterostructures and emitting at wavelengths of 730-850 nm, which were varied by altering the AlAs content in a single quantum well of 150 angstrom thickness. These structures were grown by low-temperature liquid phase epitaxy. The lowest values of the threshold current density j(th) were 380 A/cm2 for emission at lambda-l = 760 nm and 120 A/cm2 for lambda-l = 845 nm; these values were obtained for a resonator L = 700-mu-m long. In the case of AlGaAs heterojunction lasers with a resonator length L < 200-mu-m the threshold current density reached a record value (j(th) = 310 A/cm2 for L = 130-mu-m and lambda-l = 837 nm when cleaved surfaces were dust free), which made it possible to achieve low (down to 2 mA) absolute threshold currents in lasers with the mesa stripe geometry.