Abstract: The low-temperature photoluminescence (PL) and photoluminescence excitation (PLE) spectra characteristics of Al$-0.48$/In$- 0.52$/As have been studied under high pressure from 1 bar up to 92 kbar. We have obtained, for the first time, the $Gamma@-$Chi crossover critical pressure P$-c$/ (approximately 52.5 $POM 0.5 kbar), the linear pressure coefficients $alpha$+$Gamma$/ and $alpha$+$Chi$/ (7.9 meV/kbar and $MIN@2.9 meV/kbar, respectively) at helium temperature. By measuring temperature and excitation intensity dependences of the PL spectra together with the PLE spectra, we have demonstrated that the low-temperature luminescence of the Al$-0.48$/In$-0.52$/As is not excitonic but due to (D$DGR@, A$DGR@)transitions with a relatively deep acceptor of 68 meV, which occurs in both the direct- and indirect-band gap. We suggest that the shallow donor ground state associated with the $Chi@- and $Gamma@-conduction bands seem to be tied quite rigidly to these conduction bands. Variations in the donor binding energies with the pressure and the direct- indirect crossover seem to be minor. !23
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