Donor-electron transitions between states associated with the X1c and X3c conduction-band minima in GaP

Transitions from the ground states of Si, Te, and S donors associated with the lowest X conduction band have been observed to excited donor states associated with the next-higher X conduction band as well as transitions into the higher band. The X3c-X1c interband energy is found to be 355 ± 3 meV with the conductivity effective mass in the higher band being (0.14±0.02)m0. © 1971 The American Physical Society.