Investigation of high antimony-content gallium arsenic nitride-gallium arsenic antimonide heterostructures for long wavelength application

High performance and inexpensive long wavelength (1300--1550 nm) emitting diode lasers on GaAs substrates are essential components for optical fiber communication systems. GaAs1-xNx-GaAs 1-ySby type-II heterostructures were studied as an active region on GaAs substrate for long wavelength application. Metal organic vapor phase epitaxy (MOVPE) was employed as a growth technique. The growth of Sb-containing compound semiconductors and alloys are complicated due to stringent restriction on accessible range of experimental parameters, i.e. precursor mole fractions and temperature, which otherwise leads to the formation of a second surface phase during growth. The growth mechanisms of GaSb in a MOVPE system were initially studied for trimethyl gallium (TMG)/trimethyl antimony (TMSb) and triethyl gallium (TEG)/TMSb growth chemistries to extend the understanding of the growth process and to determine suitable precursors for GaAs1-y Sby alloy growth. The effect of the growth temperature and precursor mole fractions on GaSb growth rate was determined experimentally. Reduced order kinetic models were developed for both the chemistries. The chemical model for TMG/TMSb chemistry included bounds on the surface chemistry derived for the range of V/III precursor ratio which were observed to lead to a second phase, i.e., elemental Ga or Sb, formation. The highest Sb content in the pseudomorphic GaAs1-ySby achieved was as high as 37% using TEG-TMSb-AsH3 precursors. A thermodynamic model has been developed to predict the Sb composition in the solid film for a given gas phase precursor composition and growth temperature. The growth of GaAs 1-xNx was carried out using TEG-TMSb-dimethyl hydrazine (DMHy) precursors. A high density of mid-gap states has been observed in the GaAs 1--xNx film even at a very low concentration of N (∼0.5%) due to the formation of nitrogen-related clusters. A post growth annealing treatment was employed to reduce the density of such nitrogen-related compositional inhomogeneity and suppress the density of the detrimental band tail states. Finally, the GaAs1-xNx-GaAs1-ySby type-II superlattices and 'W' structures were studied to determine their feasibility for long wavelength application. Room temperature emission has been achieved from 'W' structure after employing a post-growth annealing treatment. The emission wavelength was extended up to 1.47 mum using these heterostructures.