Far-Infrared Absorption Spectrum of Be-Related Bound Excitons in Silicon

Abstract
The first measurement of the far-infrared absorption spectrum of a bound exciton is reported. This spectrum reveals the odd-parity excited states of the exciton, which cannot be observed by other means. The excited-state spectrum is found to be in excellent agreement with those of acceptors in Si, verifying earlier predictions of the level structure for isoelectronic bound excitons.