Franssen, G. and Gorczyca, l. and Suski, T. and Kamińska, A. and Pereiro Viterbo, Juan and Muñoz Merino, Elias and Lliopoulus, E. and Georgakilas, A. and Che, S.B. and Ishitani, Y. and Yoshikawa, A. and Christensen, N.E. and Svane, A.
Bowing of the band gap pressure coefficients in InGaN alloys.
"Journal of Applied Physics", v. 103
The hydrostatic pressure dependence of photoluminescence, dEPL/dp, of InxGa1−xN epilayers has been measured in the full composition range 0_x_1. Furthermore, ab initio calculations of the band gap pressure coefficient dEG/dp were performed. Both the experimental dEPL/dp values and calculated dEG/dp results show pronounced bowing and we find that the pressure coefficients have a nearly constant value of about 25 meV/GPa for epilayers with x_0.4 and a relatively steep dependence for x_0.4. On the basis of the agreement of the observed PL pressure coefficient with our calculations, we confirm that band-to-band recombination processes are responsible for PL emission and that no localized states are involved. Moreover, the good agreement between the experimentally determined dEPL/dp and the theoretical curve of dEG/dp indicates that the hydrostatic pressure dependence of PL measurements can be used to quantify changes of the band gap of the InGaN ternary alloy under pressure, demonstrating that the disorder-related Stokes shift in InGaN does not induce a significant difference between dEPL/dp and dEG/dp. This information is highly relevant for the correct analysis of pressure measurements