Characterization of Zn-Doped Ga0.86In0.14As0.13Sb0.87

Controlled doping of quaternary alloys of Ga0.86In0.14As0.13Sb0.87 with zinc is fundamental to obtain the p-type layers needed for the development of optoelectronic devices based on p-n heterojunctions. GaInAsSb epitaxial layers were grown by liquid phase epitaxy, and Zn doping was obtained by incorporating small Zn pellets in the growth melt. The chemical composition was obtained by X-ray dispersive energy microanalysis (EDX). The chemical composition homogeneity of the films was demonstrated by Raman scattering. Low-temperature photoluminescence (LT-PL) spectroscopy was used to study the influence of the Zn acceptor levels on optical properties of the epilayers. For the undoped sample, the LT-PL spectrum showed a narrow exciton-related peak centered at around 648 meV with a full width at half maximum (FWHM) of about 7 meV, which is evidence of the good crystalline quality of the layers. For higher Zn-doping, the LT-PL spectra show the presence of band-to-band and donor-to-acceptor transitions, which overlap as the Zn concentration increases. The band-to-band radiative transition (E-M) shifts to lower energies as Zn doping increases due to a band-filling effect as the Fermi level enters into the valence band, which might be used to estimate the hole concentration in the grown samples.