HYDROGEN-LIKE ULTRASHALLOW THERMAL DONORS IN SILICON-CRYSTALS

I investigated the electrical properties of annealed carbon- and nitrogen-rich Czochralski-grown silicon crystals using optical absorption and electron spin resonance, and I discovered the formation of a new kind of hydrogen-like donors, ultrashallow thermal donors (USTDs), made up of carbon, nitrogen and oxygen, and having very shallow energy levels. The donors' central-cell corrections are very small, with some of them having a negative central-cell correction peculiar to large cluster size defects. Based on the similarities between nitrogen-oxygen donors (D(N, O)s) and USTDs, I propose a formation mechanism and an atomic configuration for the USTDs. The USTDs are defects caused by interstitial carbons diffusing into the core of D(N, O) and modifying its electronic structure.