Well-thickness dependence of emission from GaN/AlGaN separate confinement heterostructures

We investigated the effects of well thickness on spontaneous and stimulated emission (SE) in GaN/AlGaN separate confinement heterostructures (SCHs), g rown by low-pressure metalorganic chemical vapor deposition. The SCH wells are unstrained and lattice-matched to a GaN buffer layer. Our series of SCH s had GaN well thicknesses of 3, 5, 9, and 15 nm. We explain the spontaneou s emission peak energy positions of the SCHs in terms of spontaneous and st rain-induced piezoelectric polarizations. At 10 K, the carrier lifetime was found to be lowest for a 3 nm well, and the SE threshold was lowest for a 5 nm well. We show that the screening of the piezoelectric field and the el ectron-hole separation are strongly dependent on the well thickness and hav e a profound effect on the optical propel-ties of the GaN/AlGaN SCHs. The i mplications of this study on the development of near- and deep-ultraviolet light emitters are discussed. (C) 2001 American Institute of Physics.