{100} Surfaces of Diamond, Silicon, Germanium, and Cubic Silicon Carbide

Abstract

On Si(001) and Ge(001) surfaces, the formation of dimers reduces the total energy. In this regard, diamond- and zincblende-structure semiconductors show the same behavior. Furthermore, the surface band structure of both types of semiconductors is semiconducting. On compound semiconductors this is due to the large energy difference between the dangling bonds at surface cations and anions. This causes the dangling bonds to become completely occupied at surface anions but to remain empty at surface cations. Therefore, the surface dimers, which are always formed between like atoms, are symmetric. On {100} surfaces of the elemental semiconductors, on the other hand, the dimers are tilted, since at one of the dimer atoms the dangling bond is occupied and at the other, empty. At low temperatures, these tilted dimers arrange in a c(4 × 2) reconstruction which exhibits an order-disorder transition below room temperature. Consequently, a 2 × 1 reconstruction is observed at room temperature.