Semiconductor nanocomposites consisting of primary phase in the form of hard nanocrystalline SiC matrix and the secondary nanocrystalline semiconductor phase were obtained by high-pressure zone infiltration. The technique was similar to that recently used by us for synthesis of superhard and metal-ceramic nanocomposites based on nanocrystalline diamond and SiC powder. The synthesis process occurs in three stages: (i) the nano-powder of SiC is compacted, (ii) the temperature is increased above the melting point of GaAs and the pores are being filled with liquid, (iii) upon cooling GaAs nanocrystallites grow in the pores. The process is performed under pressures up to 8GPa and temperatures up to 1600K. Under extreme pressures the liquid phase penetrates the pores of sizes smaller than 10 nm. Synthesis of nanocomposites was performed using toroid-type high-pressure apparatus in Warsaw (sample size φ 4x5 mm). Commercially available nanocrystalline SiC and powders synthesised at CEA, Saclay, from gaseous mixtures of silane with hydrocarbons were used as SiC matrices.

X-ray diffraction studies were performed using laboratory diffraction equipment. Phase analysis, grain size distribution function and also macro- and micro-strains present in the synthesised materials were examined. Microstructure of the synthesised materials was characterised using Scanning Electron Microscopy (SEM) equipped with microprobe. Far-infrared reflectivity and Raman spectroscopy techniques showed characteristic LO and TO phonons of both GaAs and SiC materials and allowed to trace built-in strains.