We investigate the stability and electronic structure of 1×2 and 2×2 GaAs(001):Te and InAs(001):Te surfaces with different degrees of tellurium coverage (thetaTe = <img src="http:/img/fbpe/bjp/v29n4/a4414.gif" alt="a4414.gif (106 bytes)" align="absmiddle">, <img src="http:/img/fbpe/bjp/v29n4/a4412.gif" alt="a4412.gif (100 bytes)" align="absmiddle">, <img src="http:/img/fbpe/bjp/v29n4/a4434.gif" alt="a4434.gif (104 bytes)" align="absmiddle">, 1), by means of rst-principles pseudopotential calculations within density-functional theory. The adsorption stability decreases as the tellurium coverage increases. The adsorption on InAs(001) is more stable than on GaAs(001). As-Ga (or As-In) bonds for the uppermost As atoms are s²p² -like (nearly planar), while the Te bonds at the surfaces are sp³-like. The hetero-dimers in thetaTe = <img src="http:/img/fbpe/bjp/v29n4/a4412.gif" alt="a4412.gif (100 bytes)" align="absmiddle"> modify the character of GaAs(001):Te and InAs(001):Te surfaces resulting in a semiconductor structure.
