FIR lasing based on group V donor transitions in silicon

Abstract The observation of population inversion and far-infrared emission from shallow donor transitions in silicon is reported. Silicon crystals doped with phosphor and bismuth have been optically excited by radiation from a CO 2 laser. For Si : P, the population inversion is due to the suppression of acoustical phonon assisted intracenter relaxation between the 2p 0 and 1s(E) states and stimulated emission from the transition between these states has been observed. For Si : Bi, the population inversion is due to a resonance interaction with optical phonons which deplete the 2p 0 state. In this case only spontaneous emission was detected. The experimental results are compared with theoretical calculations and found to be in good agreement.