The photoluminescence properties of metal-organic chemical vapor depos
ition GaAs:Er were investigated as a function of temperature and appli
ed hydrostatic pressure. The I-4(13/2)-->(I15/2Er3+)-I-4 emission ener
gy was largely independent of pressures up to 56 kbar and temperatures
between 12 and 300 K. Furthermore, no significant change in the low t
emperature emission intensity was observed at pressures up to and beyo
nd the Gamma-X crossover at similar to 41 kbar. In contrast, AlxGa1-xA
s:Er alloying studies have shown a strong increase in intensity near t
he Gamma-X crossover at x similar to 0.4. These results suggest that t
he enhancement is most likely due to a chemical effect related to the
presence of Al, such as residual oxygen incorporation, rather than a b
and structure effect related to the indirect band gap or larger band g
ap energy. Modelling the temperature dependence of the 1.54 mu m Er3emission intensity and lifetime at ambient pressure suggested two domi
nant quenching mechanisms. At temperatures below approximately 150 K,
thermal quenching is dominated by a similar to 13 meV activation energ
y process which prevents Er3+ excitation, reducing the intensity, but
does not affect the Er3+ ion once it is excited, leaving the lifetime
unchanged. At higher temperatures, thermal quenching is governed by a
similar to 115 meV activation energy process which deactivates the exc
ited Er3+ ion, quenching both the intensity and lifetime. At 42 kbar,
the low activation energy process was largely unaffected, whereas the
higher activation energy process was significantly reduced. These proc
esses are proposed to be thermal dissociation of the Er-bound exciton,
and energy back transfer, respectively. A model is presented in which
the Er-related electron trap shifts up in energy at higher pressure,
increasing the activation energy to back transfer, but not affecting t
hermal dissociation of the bound exciton through hole emission. (C) 19
97 American Institute of Physics.