FORMATION OF NANOSCALE FILMS OF THE (Y2O3–Fe2O3) ON THE MONOCRYSTAL InP

Abstract

Purpose. YFeO3 is distinguished by a variety of important practical properties (multiferroic, semiconductor, photocatalyst) in the visible region and others. The economic feasibility of the use of materials based on it is due to the highest prevalence of Yttrium among the entire range of rare-earth elements. New properties may appear in fi lms of the nanoscale thickness range; however, their synthesis by simple, economical, and technologically advanced methods is not an easy task. The purpose of this work was the synthesis of fi lms of nanoscale fi lms (Y2O3–Fe2O3) system on InP monocrystals, the determination of their composition and surface characteristics. Methods and methodology. Films of the nanoscale thickness range (laser, spectral ellipsometry) of the system (Y2O3-Fe2O3) on monocrystal InP were formed by centrifugation from a nitrate solution. For their primary treatment, thermal annealing (TA) or pulsed photon processing (PPP) methods were used; for the subsequent thermal oxidation of the formed heterostructures, samples without annealing were used. The phase composition was determined by X-ray diffraction analysis (XRD) and the surface characteristics were determined by atomic force (AFM) and scanning tunneling microscopy (STM). Results. The results of the study demonstrated, that fi lms that were grown without annealing are single-phase and consist of YFe2O4. The fi lms that were thermally annealed at 200 °С for 120 min were two-phase fi lms, and contained YFe2O4 and Fe2O3 with Fe3O4 (X-ray diffraction analysis). The most promising fi lms for further use were fi lms subjected to PPP in the regime of 50 J/cm2 for 0.4 s and thermal oxidation with the process parameters of 450 –550 °С for 10–60 min, in which YFe2O4 and YFeO3 were present. The results of AFM and STM indicated that annealing of samples with deposited layers of ferrite with subsequent thermal oxidation promoted the reduction of the grain size on the surface of the grown fi lm, but increases the average surface roughness compared to unannealed samples. Conclusions. Nanoscale fi lms of the (Y2O3–Fe2O3) system on monocrystal InP were synthesized by centrifugation, their compositions that correspond to various types of pretreatment and surface characteristics before and after thermal oxidation were established. We concluded that the most promising fi lms for further use were those that underwent IPP or thermal oxidation and contained YFe2O4 and YFeO3. Regulation of the ratio of these phases in the grown fi lms of the nanoscale thickness range on InP opens up the possibility of targeted control of their characteristics.

Keywords

• yttrium ferrites
• thin fi lms
• precipitation and centrifugation
• heterostructures
• indium phosphide
• thermal oxidation
• pulsed photon processing.