Heterogeneous material systems

Compound Semiconductor with High Absorption

For thin film solar cells highly absorbing semiconductors are needed to assure full utilization of the incident light.
Compound semiconductors offer a wide range of materials with high absorption and suitable band gaps. We investigate those materials that have been proven to show the highest potential worldwide.
Cu-chalcopyrite solar cells based on Cu(In,Ga)Se2 with a band gap 1.1eV have achieved efficiencies of almost 20%.

Our research interest focusses on Cu-chalcopyrites with higher band gaps for better adjustment to the solar spectrum, for higher open circuit voltages, reducing the resistive losses, and for top cells in tandem devices.
Polycrystalline and epitaxial films of Cu(In,Ga)S2 and Cu(In,Ga)Se2 are prepared by a number of established and novel methods. Defect structure, electrical transport, recombination paths and device performance are investigated.

The activities are organized along the following topics:

  1. Cu(In,Ga)S2 by PVD1
  2. CuGaSe2 by PVD
  3. CuGaSe2 by MOCVD2/MOPVE
  4. CuGaSe2 by CVD3
  5. CuGaSe2 by CCSVT4

1 (physical vapor deposition)
2 (metal organic chemical vapour deposition)
3 (chemical vapour deposition)
4 (chemical close space vertical transport)