Tunneling spectroscopy of the GaAs(110) surface

The scanning tunneling microscope is used to study the spectroscopy of p‐type, n‐type, and oxygen‐covered GaAs(110) surfaces. On the clean surface, three components of the current are identified—tunneling out of valence‐band states, tunneling into conduction‐band states, and tunneling through dopant‐induced states in the semiconductor. The results are compared with a theoretical computation of the tunneling current, including band bending in the semiconductor. Good agreement between theory and experiment is obtained only when tunneling through the space‐charge region of the semiconductor is included. On the oxygen‐covered surface, the spectroscopic results show evidence of band bending due to the oxygen adsorbates.