Two-dimensional electronic structure of the GaAs(110)-Bi system

The occupied electronic structure of the GaAs(110)-Bi(1×1) monolayer system has been studied using angle-resolved photoelectron spectroscopy with a synchrotron-radiation source. The overlayer system possesses at least three detectable surface states (S, S and S) with two-dimensional character. Both the state with the lowest (S) and the state with the highest (S) binding energy are clearly visible over a large portion of the (1×1) surface Brillouin zone. The intermediate state (S) was observed along » X» and also in the neighborhood of X». The intensity of all three states exhibits a predominantly pz-like dependence on the polarization of the synchrotron light. However, S possesses a greater component of pxy-like character than either S or S. At the zone center, S is situated 0.5 eV above the valence-band maximum, and it disperses downwards by 1.0 eV to X», and by 0.8 eV to X». At M» it has its binding-energy maximum, 1.3 eV below the energetic position at "». The two-dimensional electronic structure of this system is compared with that of the closely related GaAs(110)-Sb(1×1) monolayer system and with the results of first-principles calculations. © 1991 The American Physical Society.