Characterization of highly doped Ga_0.86In_0.14As_0.13Sb_0.87 grown by liquid phase epitaxy

Ga0.86In0.14As0.13Sb0.87layers lattice-matched to (100) Te-GaSb have been grown using the liquid phase epitaxy technique under supercooling conditions. N and p type layers were grown by adding tellurium or zinc in a wide range of molar fraction in the growth solution. By Raman spectroscopy, the structural quality of the epilayers was characterized. The Raman spectra show that the layers become more defective as the dopant molar fraction is increased, n- or p-type. Two main bands are observed in the Raman spectra centered at 230 and 245 cm-1that depend strongly on the incorporated dopant molar concentration (Te or Zn), which are assigned to the observed vibrational modes of GaAs-like and (GaSb+InAs)-like mixture. The low-temperature photoluminescence of n (or p)-type GaInAsSb was measured as function of dopant concentration added to the melt solution. The photoluminescence spectra were interpreted taking into account the nonparabolicity of the conduction (or valence) band. Both the band filled as well as band tailing effects due to Coulomb interaction of free carriers with ionized impurities and shrinkage due to exchange interaction between free carriers were considered in order to properly be taken into account for the observed features of the photoluminescence spectra. It is shown that the band-to-band transition energy can be used to estimate the free carrier concentration in GaInAsSb for a wide range of dopant concentration.