ELECTROLUMINESCENCE IN VERTICALLY ALIGNED QUANTUM-DOT MULTILAYER LIGHT-EMITTING-DIODES FABRICATING BY GROWTH-INDUCED ISLANDING

A molecular beam epitaxy (MBE) growth-induced islanding process has be en used to form self-organized multiple quantum dot layers, in which q uantum dots from different layers are vertically aligned in columns an d are electronically coupled. These structures are used as the active region in light-emitting diodes operating at room temperature. Light-e mitting diodes are investigated using quantum dot columns containing s ingle, 5 and 10 InAs quantum dots. These diodes emit light over a broa d band with typical spectral linewidths of 120 nm, peaked between 1000 and 1100 nm. In addition to the quantum dot spectral feature, a spect ral feature from a thin quantum well region, integral to the quantum d ot formation process, is seen in the single quantum dot diode, but is eliminated in diodes with active regions containing columns of multipl e quantum dots. (C) 1996 American Institute of Physics.