[14p-F201-1~14] 15.7 Crystal evaluation, impurities and crystal defects

[14p-F201-12] Ground-State Splitting of Ultrashallow Thermal Donors in Si Crystals

〇Akito Hara¹, Teruyoshi Awano¹ (1.Tohoku Gakuin Univ.)

Keywords:semiconductor, silicon, donor

We previously reported on the formation of ultrashallow thermal donors (USTDs) in Czochralski silicon (CZ Si) crystals. The USTDs consist of light-mass elemental impurities such as carbon, hydrogen, and oxygen. To the best of our knowledge, these are the shallowest hydrogen-like donors, with negative central-cell correction, in Si. We observed ground-state splitting of USTDs by using far-infrared optical absorption at different measurement temperatures. The upper ground-state levels are approximately 4 meV higher than those of the ground-state levels. This energy level is also consistent with that obtained by thermal excitation from the ground-state to the upper ground-state. This is the direct evidence that wave function of ground-state of USTDs are made up of linear combination of those of conduction band minimum.