Quantum well lasers with InAs monolayers in the active region grown at low temperature by atomic layer molecular beam epitaxy

Abstract

Strained-layer quantum well lasers have been grown at low substrate temperature (350°C) by atomic layer molecular beam epitaxy (ALMBE). A series of five separate confinement laser structures has been grown. Active regions consist of 80 A of GaAs in which n InAs monolayers are inserted separated by 3 GaAs monolayers, with n = 1, 3, 5 and 7. A sample with 100 Å Ga 0.8In 0.2As active region was also grown at low temperature for comparison. Structural quality is studied by X-ray diffraction. Optical characterization has been performed, and the results are compared with calculations by a four-band envelope-wavefunction method. Broad area lasers have been fabricated, and their performances are studied as a function of increasing InAs content. Lasers with GaAs active regions including InAs monolayers show threshold currents comparable to that of the GaInAs alloy laser, for n≤5 monolayers. These results prove the feasibility of ALMBE for the low temperature growth of strained layer lasers.