Silicon based Heterostructures

Heterostructures represent a basic structure in solid state physics and electronic devices (field effect transistors, III-V optoelectronic, solar cells).

They allow:

• To combine the best suitable properties of different solids
• Passivation of interface states
• To build bridges between organic and inorganic solids

Especially the a-Si:H/c-Si heterojunction is in our focus at the moment . This hetero junction offers the possibilty of a well passivated c-Si surface. The chemical vapour deposition of a-Si:H at low temperatures (T<300°C) enables the realization of a complete low temperature processing on thin poly-crystalline silicon films on glass or on silicon wafers for high efficiency hetero-solar cells. These cells show an efficiecy of up to 24 % in case of a "classical" cell design with front contact. Alternative designs offer more than 24 % as shown in numerical simutaltion done by AFORS-HET. The scheme of such a cell-structure is presented in fig.2.