Very narrow graded-barrier single quantum well lasers grown by metalorganic chemical vapor deposition

Abstract

Graded‐barrier GaAs‐GaAlAs single quantum well lasers have been fabricated, utilizing the graded‐index separate confinement heterostructure to confine carriers and optical field. Very low threshold current densities have been observed down to a well size of 75 Å. The lowest threshold current density observed is 240 A/cm² for a 100‐Å heavily doped quantum well laser. This experimental value agrees very well with the calculated threshold current density obtained from detailed band calculation and is attributed to the enhanced gain‐current characteristic in these quantum well structures.