Analysis of nitrogen incorporation mechanisms in GaAs1−xNx/GaAs epilayers grown by MOVPE

The incorporation of nitrogen in Ga(As,N)/GaAs grown by metalorganic vapor phase epitaxy has been investigated as a function of growth conditions. The evolution of the solid composition was studied as a function of growth temperature between 500 and 600°C, and gas-phase composition. For instance, at growth temperatures of 510–560°C, the solid composition varies slowly with T, with an apparent activation energy of 0.6 eV. For T>560°C, an exponential decrease is dominantly observed with an apparent much higher activation energy of 3.7 eV. The effect of the growth temperature is analyzed, taking account for the different surface reaction mechanisms. The observed transition between the two regimes is attributed to an increased desorption of nitrogen at high temperatures. In light of experimental results, we propose a surface kinetics model based on the competitive adsorption of group V precursors. We also deduced an energy barrier for adsorption of group V species.