Elastic and inelastic tunneling of photoelectrons from the dimensional quantization band at a p +-GaAs-(Cs,O) interface into vacuum

The photoemission of electrons from a p + -GaAs surface with negative electron affinity was studied experimentally at 4.2 K. A narrow peak and its phonon replicas were observed in the distribution of emitted electrons over the energies of longitudinal motion. These replicas are caused by elastic and inelastic electron tunneling from the bottom of the dimensional quantization band in the near-surface spatial-charge region through the potential barrier of the (Cs,O) activating coverage with emission of LO phonons. The measured position of the peak corresponding to elastically tunneling electrons is close to the calculated one.