InGaN/GaN multiple quantum wells grown by metalorganic vapor phase epitaxywith mass transport

We report on studies of In0.12Ga0.88N/GaN heterostructures with three 35-An gstrom-thick quantum wells (QWs) grown on sapphire substrates by metalorgan ic vapor phase epitaxy with employment of mass transport. The structure is demonstrated to show good structural and optical properties. The threading dislocation density is less than 10(7) cm(-2) for the mass-transport region s. The photoluminescence (PL) spectrum is dominated by the rather narrow ne ar-band gap emission at 2.97 eV with a linewidth of 40 meV. This emission h as a typical PL decay time about 5 ns at 2 K within the PL contour. With in creasing excitation intensity, an additional transition with longer decay t ime (about 200 ns) is enhanced at energy about 2.85 eV. The position of thi s line depends strongly on the excitation power. We explain the data in ter ms of a model, where the PL is a result of contribution from at least two n onequivalent QWs, which could be realized due to a potential gradient acros s the layers. (C) 2000 American Institute of Physics. [S0003- 6951(00)04337 -0].