Transmission electron microscopy study of Ge implanted into SiC

Hexagonal 6H- and 4H-SiC wafers were implanted with (1-1.5) x 10(16) cm(-2) germanium ions at room temperature and at 700degreesC with subsequent annealing between 1000 and 1600degreesC. Structural changes in the SiC matrix were studied in detail by means of transmission electron microscopy (TEM). After implantation at room temperature the hexagonal SiC matrix becomes amorphous and, after annealing, recrystallizes into cubic SiC. The latter process was accompanied by the creation of voids and cracks. In case of high-temperature (700degreesC) implantation, where amorphization was avoided, no polytype change in as-implanted and annealed SiC wafers was observed. In annealed samples nanocrystalline precipitates with high Ge content were observed in high-resolution TEM images.