Impact of the atomic ordering degree on the ferroelectric properties of GaInP$_2$ alloys

We present measurements of the surface potential (Kelvin probe microscopy), structure (X-ray diffraction, transmission electron microscopy and Raman spectroscopy) and optical transitions (photoluminescence) of CuPt$_\mathrm{B}$ atomically ordered GaInP$_2$ layers grown by metal-organic vapor phase epitaxy on GaAs (001) substrates at group V/III flux ratio 15–150 and substrate orientation 0 and 6$^\circ$. It is shown that the ordering degree in the layers varies in the range 0.05–0.56. Analysis of surface potential data showed suppression of the built-in electric field and the effect of switching the sign of the field, i.e., relaxation of atomically ordered domains during sample puncture, caused by the martensitic transition, for $x<$ 0.3.