Laterally injected low-threshold lasers by impurity-induced disordering

Novel laterally injected lasers were fabricated by impurity-induced disordering (IID). The laterally injected IID (LID) lasers have a self-aligned structure and planar configuration; its processing procedures are almost identical to that used for our recently reported vertically injected IID lasers, and are considerably simpler than those of any other laterally injected laser yet reported. The LID lasers have a minimum threshold current Ith=3.2 mA (typical Ith=4 mA) and a maximum light output 11 mW, with a differential quantum efficiency ηd=32% per facet under room-temperature continuous-wave operation. The LID lasers can also be injected vertically by deliberately using an n+-doped (instead of semi-insulating) GaAs substrate and making additional ohmic contacts on the bottom surface of the wafer. A number of interesting aspects about the LID lasers were revealed by comparing the L-I characteristics of the laser under different injection modes, and by studying the I-V characteristics of different combinations of the top and bottom ohmic contacts.