Novel semiconductor infrared lasers based on III-V materials by molecular beam epitaxy

Semiconductor lasers in the infrared wavelength range have been attracting intensive research effort due to their applications in optical communication, remote sensing, spectroscopy, and environmental monitoring. In this work, we investigated the novel semiconductor laser structures and materials in the infrared wavelength range of 2∼5mum.; InGaAsSb/AlGaAsSb type-I quantum-well (QW) lasers based on GaSb substrate are the dominant choice for semiconductor laser in the 2∼3mum range. However, their temperature stability is still relatively poor and their room-temperature (RT) emission wavelength is generally limited up to 2.8 mum. In this work, novel strain-compensation structures have been employed into InGaAsSb/AlGaAsSb quantum well (QW) lasers by introducing tensile-strained AlGaAsSb barriers. The relatively high arsenic composition in AlGaAsSb barriers lowers the valence band edge and the hole energy level, leading to an increased hole confinement and improved laser performance. Moreover, the tensile strain in AlGaAsSb barriers can reduce the average strain in the QW structure and allow more indium in the InGaAsSb well, resulting into extended lasing wavelength. A 60% external differential efficiency in pulsed mode was achieved for 1000-mum long lasers emitting at 2.43 mum. A characteristic temperature (T0) as high as 163K and a lasing-wavelength temperature dependence of 1.02 nm/°C were obtained at RT. For 2000 x 200 mum2 broad-area three-QW lasers, a low pulsed threshold of 275 A/cm2 was measured. A 2.82 mum emission wavelength in pulsed mode along with a 660 A/cm 2 threshold current density was obtained at RT. By further increasing the indium and arsenic compositions into the wells and barriers respectively, RT pulsed lasing at a record-long wavelength of 2.89 mum has also been achieved.; In order to further improve the optical and structural quality, digital tensile-strained AlGaAsSb barriers was employed to avoid the growth interruption at the well/barrier interface during MBE growth. Based on these high-quality InGaAsSb/AlGaAsSb SCMQW(strain-compensated multiple quantum wells) with digital barriers, a RT low-threshold current density of 163A/cm2 and a record-high T0 of 165°C were achieved for 2.4 mum InGaAsSb lasers which can operate excellently above 100°C. (Abstract shortened by UMI.)...