Indium incorporation and emission wavelength of polar, nonpolar and semipolar InGaN quantum wells

InGaN quantum wells were grown by metal organic vapor-phase epitaxy on polar (0 0 0 1), nonpolar (1 0 (1) over bar 0) and on semipolar (1 0 (1) over bar 2), (1 1 (2) over bar 2), (1 0 (1) over bar1) as well as (20 (2) over bar 1) oriented GaN substrates. The room-temperature photoluminescence (PL) and electroluminescence (EL) emission energies for quantum wells grown on different crystal orientations show large variations of up to 600 meV. The following order of the emission energy was found throughout the entire range of growth temperatures: (1 0 (1) over bar 1) < (1 1 <(2)over bar> 2) = (0 0 0 1) < (2 0 <(2)over bar> 1) < (1 0 <(1)over bar> 0)= (1 0 (1) over bar 2). In order to differentiate between the effects of strain, quantum-confined stark effect (QCSE) and indium incorporation the experimental data were compared to k. p theory-based calculations for differently oriented InGaN QWs. The major contribution to the shift between (1 0 (1) over bar 0) and (0 0 0 1) InGaN quantum wells can be attributed to the QCSE. The redshift between (1 0 (1) over bar 0) and the semipolar (1 0 (1) over bar 2) and (2 0 (2) over bar 1) QWs can be attributed to shear and anisotropic strain affecting the valence band structure. Finally, for (1 1 (2) over bar 2) and (1 0 (1) over bar 1) the emission energy shift could be attributed to a significantly higher indium incorporation efficiency.