A NEW RESONANCE OF THE SURFACE SHG FROM GAAS(001) IN AIR

The reflected optical second harmonic (SH) intensity from GaAs(001) ha s been measured in air as a function of the incident photon energy. A resonance enhancement peak was found at similar to 1.45 eV in the p-po larized input and p-polarized output (p-in/p-cut) configuration. Becau se the sum frequency generation (SFG) intensity shows a one-photon res onance at the same photon energy, the observed structure in the SH int ensity curve is also due to a one-photon resonance. The bulk SH respon se of GaAs was separately observed in the p-in/s-out polarization conf iguration and does not show a resonance at this photon energy. Thus it is concluded that the observed resonance at similar to 1.45 eV origin ates from the oxidized surface of GaAs(001). (C) 1998 Elsevier Science B.V. All rights reserved.