Abstract
Using electron tunneling, we report the first direct spectroscopic measurement of the Coulomb correlation gap in the density of states of a nonmetallic doped semiconductor Si: B. In agreement with analytic models, is found to have a nearly parabolic energy dependence, resulting in a "soft" zero at the Fermi energy, with a gap width ≈0.75 meV. Resistivity measurements show that this energy governs the observed crossover temperature between noninteracting and correlated hopping transport.
- Received 7 June 1995
DOI:https://doi.org/10.1103/PhysRevLett.75.4266
©1995 American Physical Society