Two and four quantum-well (QW) GaInAsSb-AlGaAsSb lasers emitting at 2 /spl mu/m are reported. In comparison to previously published data, it is found that higher Al content in the QW barrier improves the internal efficiency, saturated modal gain, and characteristic temperature of the lasers. These results are attributed to an increased valence band offset that provides superior hole confinement in the GaInAsSb QW. A differential efficiency of 74% is observed at 25/spl deg/C under pulsed conditions for a 900-/spl mu/m cavity length, 2-QW device, and a record characteristic temperature of 140 K is measured for a 4-QW laser.

The effect of increased valence band offset on the operation of 2 μm GaInAsSb-AlGaAsSb lasers

High performance mid-infrared (2–5 μm) laser diodes are needed for applications such as high resolution and high sensitivity chemical gas analysis and atmospheric pollution monitoring. The goal is to obtain continuous wave laser emission at room temperature, with output power > 1 mW. Different technologies are under investigation to reach this objective. The GaInAsSb/AlGaAsSb strained multi-quantum-well laser showed striking results in CW operation at and above room temperature and appears as a well established technology for laser emission in the 2.0–2.7 μm wavelength range. Beyond 2.7 μm, the IV–VI lasers based on the PbSe/PbSrSe system, type-II “W” quantum well lasers based on the InAs/GaInSb system, and type-II interband and intersubband III–V cascade lasers, are competitive technologies. They could all operate at room temperature or near room temperature, but only in the pulsed regime. This paper presents an overview of the state of the art of these different mid-infrared systems emitting in the 2–5 μm wavelength range. Two heterojunction laser technologies are detailed: the 2–3 μm GaInAsSb multi-quantum-well laser, and the 3–5 μm type-II and type-II “W” laser diodes.

Mid-Infrared 2—5 μm Heterojunction Laser Diodes

III-Sb-based Type-I QW Diode Lasers

High-resolution x-ray diffractometry (HRXRD) and transmission electron microscopy (TEM) are employed to characterize a quaternary IIIxIII1−xVyV1−y AlGaAsSb/GaInAsSb multiple quantum well (MQW) heterostructure. A method for uniquely determining the chemical composition of the strained quaternary quantum well, information previously thought to be unattainable using HRXRD, is thoroughly described. The misconception that HRXRD can separately find the well and barrier thickness of a MQW from the pendellosung fringe spacing is corrected and, thus, the need for TEM is motivated. Computer simulations show that the key in finding the well composition is the intensity of the higher order satellite peaks in the diffraction pattern. For the AlGaAsSb/InGaAsSb MQWs analyzed in this work, the variation in the intensity of the third-order satellite peak is identified as a sensitive measure of the quantum well composition. Using HRXRD on an MQW semiconductor laser device layer, the ability to resolve this higher order pea...

High-resolution x-ray and transmission electron microscopic analysis of a GaInAsSb/AlGaAsSb multiple quantum well laser structure

http://esl.ecsdl.org/content/4/8/C55.full.pdf

Pulsed Anodization Etching for the Fabrication of Ridge-Waveguide Structures in Mid-infrared InGaAsSb Quantum Well Laser Material

Compressively strained 2 micrometer GaInAsSb quantum well lasers with large valence band offsets and broadened waveguides display a record characteristic temperature, T 0 equals 140 degrees Kelvin for a 4-QW laser and a differential efficiency of 0.74 for a pulsed 2-QW device. The T 0 of these antimonide lasers is 65% more than that reported for phosphide-based lasers operating at 2 micrometer wavelength. A room-temperature threshold current density as low as 173 A/cm 2 has been observed for a 2-QW device and 225 A/cm 2 for the 4-QW laser.

Tim C. Newell

Papers

Gain and threshold current density characteristics of 2-μm GaInAsSb/AlGaAsSb MQW lasers with increased valence band offset