Epitaxial Structure Design of a Long-Wavelength InAlGaAs/InP Transistor Laser

Abstract

The threshold condition in long-wavelength InAlGaAs/InP transistor lasers is theoretically and numerically investigated. The optical gain in the In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.58</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.42</sub> As/In(Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.4</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.6</sub> )As strained quantum well is calculated using a simplified <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> -selection model while intervalence band absorption is considered as the major intrinsic optical loss in the transistor lasers. It is found that room-temperature lasing of an <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> -InP/ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p</i> -In(Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.4</sub> Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.6</sub> )As/ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> -InP double heterostructure transistor laser is achieved only when the base thickness and doping level are within a specific narrow range. However, the selectable range is significantly expanded by means of facet coating, structure engineering, and quantum well design. By using a more compressively-strained or thicker quantum well as the active region in a separate confinement heterostructure transistor laser, it is possible to obtain a threshold current density as low as sub-100 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .