Decrease in the bond energy of arsenic atoms on the GaAs(100)-(2$\times$4)/c(2$\times$8) surface due to the effect of adsorbed cesium

It has been found experimentally that the bond energy of arsenic atoms on the GaAs(100) surface decreases under the influence of adsorbed cesium. This is manifested in the disordering of the As-stabilized surface and in a decrease of $\sim$100 K in the temperature of the transition to the Ga-stabilized (100)GaAs(4$\times$2)/c(8$\times$2) surface. This effect is caused by the redistribution of the valence electron density between the arsenic atoms in the upper layer and the gallium atoms in the lower-lying layer as a result of charge transfer from the electropositive adsorbate to the semiconductor. In combination with the analogous effect of a decrease in the bonding energy of gallium atoms on the Ga-stabilized GaAs surface upon the adsorption of electronegative adsorbates (halogens), the effect observed allows the atomic layer etching of the polar GaAs(100) face.