Crystalline Truncated Micropyramids Grown from GaAs Liquid Phase on GaP (001) Substrates

Herein, a report on the growth of crystalline truncated pyramid microstructures by liquid-phase epitaxy of Ga-As liquid phase on GaP (001) substrates under nonequilibrium (NEQ) conditions with different contact times and growth temperatures is provided. The micropyramids (MPs) have rectangular bases which are between 5 and 10 mu m long, with the long sides aligned with the [110] direction. Remarkably, the results show that the growth rates of the MP under NEQ are very high compared with those of traditional epitaxial layers grown under near-equilibrium conditions. Spatially resolved microphotoluminescence mappings reveal a spatial dependence of the near-band edge emission in both wavelength and intensity within a single MP. The measured emission-wavelength range corresponds to ternary GaAs(1-x)P(x)alloys, which attests to the diffusion of P atoms from the substrate into the MPs during growth. The content of P atoms in the MPs is confirmed by spatially resolved energy-dispersive X-ray spectroscopy. Both studies show that the concentration of P is higher in the {111} planes than in the rest of the MP. A thermodynamic argument is proposed to support the experimental findings.