C-doped GaAs and AlxGa1-xAs (0 < x < 0.39) films, grown by solid-source MBE with doping levels beyond 10(19) cm3, have been investigated by high-resolution X-ray diffraction, Hall-effect measurements and photoluminescence (PL). Comparison of X-ray and Hall data reveals that carbon is substitutionally incorporated on As sites up to C concentration of 3 X 10(19) cm-3. Sharp excitonic and free-to-bound (e-C0) transitions on the high-energy side of the PL spectra show the existence of local incorporation of C as interstitial impurity. Both these sharp transitions disappear in samples grown with high As4 beam fluxes. Moreover, in C-doped AlxGa1-xAs films grown with the same C concentration and the same AS4 flux, the free-hole density is found to increase with the AlAs mole fraction. A higher Al-C bond strength compared to Ga-C causes an increase of C on As lattice sites with respect to C-incorporated interstitially in the GaAs matrix.
STRUCTURAL AND ELECTRONIC-PROPERTIES OF GAAS-C AND ALXGA1-XAS-C GROWN BY SOLID-SOURCE MOLECULAR-BEAM EPITAXY
GIANNINI C;
1993
Abstract
C-doped GaAs and AlxGa1-xAs (0 < x < 0.39) films, grown by solid-source MBE with doping levels beyond 10(19) cm3, have been investigated by high-resolution X-ray diffraction, Hall-effect measurements and photoluminescence (PL). Comparison of X-ray and Hall data reveals that carbon is substitutionally incorporated on As sites up to C concentration of 3 X 10(19) cm-3. Sharp excitonic and free-to-bound (e-C0) transitions on the high-energy side of the PL spectra show the existence of local incorporation of C as interstitial impurity. Both these sharp transitions disappear in samples grown with high As4 beam fluxes. Moreover, in C-doped AlxGa1-xAs films grown with the same C concentration and the same AS4 flux, the free-hole density is found to increase with the AlAs mole fraction. A higher Al-C bond strength compared to Ga-C causes an increase of C on As lattice sites with respect to C-incorporated interstitially in the GaAs matrix.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
