Optical properties of the sulfur-related isoelectronic bound excitons in Si

We present a detailed spectroscopic investigation of excitons bound to two recently discovered sulfur-related isoelectronic centers in Si with photoluminescence (PL) emissions near 1.3 and 1.5 {μ}m. High-resolution photoluminescence and photoluminescence-excitation (PLE) spectroscopy were combined with the new far-infrared exciton-absorption spectroscopy (FIEAS) technique to reveal the electronic structure of these bound excitons. Striking similarities between the two centers were observed with all three techniques. Low-temperature PL reveals a low-energy dipole-forbidden ground-state transition. The FIEAS results show that the isoelectronic bound excitons have donorlike electronic excited states with electron binding energies of 65.28 and 66.21 meV for the shallow and deep centers, respectively. These energies are twice that of the donor effective-mass model. The determination of the electron binding energies by FIEAS allows the identification of many of the transitions observed in PL and PLE.