Pressure study of the ${\mathrm{N}}_{\Gamma }$ and ${\mathrm{N}}_X$ bound-state interaction in nitrogen-doped $\mathrm{Ga}{\mathrm{As}}_{1-x}{\mathrm{P}}_x$

By means of hydrostatic-pressure measurements on ${\mathrm{In}}_{1-y}{\mathrm{Ga}}_y{\mathrm{P}}_{1-z}{\mathrm{As}}_z-\mathrm{Ga}{\mathrm{As}}_{1-x}{\mathrm{P}}_x:\mathrm{N}$ heterojunctions, we examine the change in electroluminescence and thus interaction of the ${\mathrm{N}}_{\Gamma }$ and ${\mathrm{N}}_X$ bound states of N-doped $\mathrm{Ga}{\mathrm{As}}_{1-x}{\mathrm{P}}_x$. In agreement with theoretical studies, photoluminescence data at various crystal composition values (discrete points in a large range $x$) are plotted and suggest a splitting of the ${\mathrm{N}}_{\Gamma }-{\mathrm{N}}_X$ states near $x\sim 0.3$. This behavior is demonstrated in a continuous manner by the pressure behavior of the ${\mathrm{N}}_{\Gamma }$ and ${\mathrm{N}}_X$ states in the range $0.2\lesssim x\lesssim 0.38$.