| AVS 59th Annual International Symposium and Exhibition | |
| Electronic Materials and Processing | Thursday Sessions |
| Session EM-ThM |
| Session: | Processing for Ultra Low Power Electronics + Semiconductor Heterostructures I |
| Presenter: | P. Ebert, Forschungszentrum Jülich, Germany |
| Authors: | P. Ebert, Forschungszentrum Jülich, Germany S. Landrock, Forschungszentrum Jülich, Germany Y. Jiang, Peking University, China K.H. Wu, Chinese Academy of Sciences, China E.G. Wang, Peking University, China R.E. Dunin-Borkowski, Forschungszentrum Jülich, Germany |
| Correspondent: | Click to Email |
Alloying different semiconductor compounds attracted wide attention, since the materials properties of the resulting semiconductor alloy can be continuously tuned by varying the composition. Hence one can engineer semiconductor materials with, e.g., intentionally designed band gaps, lattice constants, and/or optical properties. This approach possesses a large technical and economical interest, as it is the basis for defining the wavelength of most optoelectronic devices.
For such applications, it is crucial that the newly formed semiconductor alloy has spatially homogeneous electronic properties, i.e., the original materials' properties of the individual alloyed compounds merge into the desired new properties. This is in general assumed to be the case for most three-dimensional compound semiconductor alloys. With the ever shrinking dimensions of semiconductor devices, the semiconductor alloy layers are be coming increasingly thinner. Ultimately only monolayer thin alloy layers may be needed and then the concept of a globally homogenous alloy band structure, different from that of its alloyed compounds, needs to be reassessed. The central question is if a two-dimensional semiconducting alloys would always exhibit a merged new band structure in analogy to three-dimensional semiconductor alloys, or if locally the different band structures of the constituent semiconductor compounds of the alloy persist.In this paper, we present a two-dimensional Ga-Si √3x√3 semiconductor alloy on Si(111) substrates as model system. Using atomically and momentum resolved STM and STS, we demonstrate that the electronic structure, i.e., density of states, band gap, and band structure, is atomically localized and different at Si and Ga atoms. No intermixing and formation of new alloy related electronic properties are observed, as if no alloying ever happened. This unmixed state is discussed in terms of the particular bonding structure of the two-dimensional alloy.