Magneto-Optical Studies of Excited States of the Cl Donor in CdS

We have studied the $2s$ and $2p$ levels of the Cl donor in CdS by two methods: first, by observing "two-electron transitions" in which an exciton bound to the neutral donor Cl decays, leaving the donor in its $n=2$ excited states; second, by observing Raman-scattering transitions between the $n=1$ and $n=2$ donor levels. We have accurately measured the positions of the 2pₓ, 2pz, and $2s$ levels relative to the $1s$ state to be 24.36 ±{} 0.02, 24.19 ±{} 0.02, and 23.88 ±{} 0.02 meV; the anisotropy factor α=0.054±0.005; and the electron mass m_⊥=0.190±0.002. With less precision, we have measured m_∥=0.180±0.010 and estimated the donor binding energy to be 32.7 ±{} 0.4 meV.