Generic guiding principle for the prediction of metal-induced reconstructions of compound semiconductor surfaces

We have performed extensive and systematic ab initio calculations to substantiate a recently proposed generalized electron counting (GEC) rule that governs the rich patterns of compound semiconductor reconstruction induced by metal adsorption. In this rule, the metal adsorbates serve as an electron bath, either donating or accepting the right number of electrons, with which the binary host system chooses a specific reconstruction under the classic electron counting rule and, meanwhile, the adsorbates stay in their optimal valency. The GEC rule is applied to different GaAs surfaces deposited by various classes of metal adsorbates, leading to a number of possible reconstructions, which can be further confirmed by first-principles calculations and/or experiments. The alkali-metal adsorption on the GaAs(110) surface up to the saturate coverage is a perfect example of the GEC rule. The application of the GEC rule to the prototype system of Mn/GaAs(001) not only predicts possible reconstruction patterns over a wide range of coverage but also provides an underlying link between the reconstruction structures and the local magnetic moments of the metal adsorbates. For Au/GaAs(100), we demonstrate the application of the GEC rule to those systems where metal adsorbates form covalent bonds with the substrate. The GEC rule, as a generic principle, is expected to be applicable to more metal-adsorbed compound semiconductor surfaces.