Atmospheric pressure organometallic vapor-phase epitaxial growth of (AlxGa1−x)0.51In0.49P (x from 0 to 1) using trimethylalkyls

Abstract

(Al_xGa_1−x)_0.51In_0.49P layers, lattice matched to (001)‐oriented GaAs substrates, have been grown throughout the entire aluminum composition range from x=0 to 1.0 by atmospheric pressure organometallic vapor‐phase epitaxy (OMVPE), using trimethylaluminum (TMAl), trimethylgallium (TMGa), trimethylindium (TMln), and phosphine (PH₃) as source materials in a horizontal reactor. The growth temperature was held constant at 680 °C. Excellent surface morphologies were obtained over the entire composition range. Unlike previously reported results, neither high growth temperatures nor low pressures were needed in order to obtain good‐quality, high‐x (Al_xGa_1−x)_0.51In_0.49P alloys using trimethylalkyls. Photoluminescence (PL) was observed, even at 300 K, for all samples with Al solid compositions of x≤0.52. The results show that the energy band gap measured by PL at room temperature for this material varies as E_g=1.9 +0.6x, in accord with previous studies. It was found that the PL emission intensity was nearly constant at 10 K with increasing x in the range from 0 to 0.52. This contrasts with earlier published results which showed a decreasing PL intensity for the higher values of x. The 300‐K PL intensity was almost a constant for x≤0.3 and gradually decreased with increasing Al content for x>0.30. The dependence is nearly that predicted from a simple calculation based on the relative occupancies of the Γ and X conduction bands using a constant minority‐carrier lifetime. The PL full width at half maximum (FWHM) for x=0 was 7.2 meV at 10 K and 35 meV at 300 K. These are the narrowest reported results to date. For x=0.48, the FWHM was 31 meV at 10 K and 78 meV at 300 K. It was observed that at both 10 and 300 K, the FWHM increased slowly with increasing aluminum concentration.