Lasers with tunneling injection and separated optical and electrical confinement (TI SCH)

A novel type of semiconductor laser based on the tunneling injection through thin AlAs barriers surrounding QW GaAs active region has been developed. To stress a new type of injection mechanism involved the laser have been called TI SCH (Tunneling Injection Separate Confinement Heterostructure). They were designed to bypass thermalization and allow electron injection directly into (n=1) confined level in QW. The penalty paid in a form of increased threshold current, which is roughly twice that of the standard SQW SCH laser, is fully recompensated by higher modulation bandwidth of the device and red emission from Al-free active region. In the case of multiquantum well (TI SCH MQW) structures, very low threshold current densities, of the order of 250 A/cm2 and transparency currents 0f 145 A/cm2, have been achieved for the 4QW active region, which to the best of our knowledge are record values for MQW lasers. The structures were grown by the solid source MBE at high substrate temperatures and V/III flux ratios adjusted separately for AlGaAs cladding layers and GaAs active regions by using two effusion cells. (author)