Long Lifetime State of Shallow Donor Centres for Silicon Based THz Sources

Impurity centres in high purity silicon with ionization energies 38.32 and 40.09meV are observed by photo-thermal ionization spectroscopy measurements. Their typical shallow donor characteristics are approved by good agreement with theoretic evaluation under varying magnetic fields. The 2p₀ state lifetime of one donor centres are more than 3 times longer than that of phosphorus in the same silicon sample. Compared to phosphorus which has been already successfully exploited to produce silicon-based THz radiations, this shallow donor centre has a pronounced enhancement on lifetime and quality factor of population inversion level. Hence, silicon with this donor centre would be a potential excellent candidate to develop improved silicon-based THz sources.