Individual thermal donor species studied with high-field magnetic resonance

Thermal donors generated in p-type boron-doped Czochralski-grown silicon by a 450 degrees C heat treatment have been studied by high-field magnetic re sonance spectroscopy. The experiments were conducted at a microwave frequen cy of 140 GHz and in a magnetic field of approximately 5 T. The symmetry of the g-tensor of four individually resolved Si-NL8 species was determined. It turned out that only one of the early species shows a true orthorhombic symmetry. Upon prolonged heat treatment times the relative concentration of the most anisotropic (early) species showed a clear decrease, while that o f the later species increased.