Surface electron microscopy for understanding heteroepitaxy of GaP on silicon

• Applicants: Professor Dr. Winfried Daum; Professor Dr. Thomas Hannappel
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2013 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 221756164

Lattice-matched III-V semiconductor systems grown on Si substrates offer a promising potential for applications as high-efficiency multi-junctions solar cell as well as for integration of optoelectronics into Si technology. However, crystal defects in the III-V epi-layers have so far impeded a major breakthrough in industrial implementation of III-V/Si technology. Using a variety of complementary electron microscopy methods, mainly LEEM but also STM, SAM and SEM, this project aims at quantification and characterization of such crystal defects in GaP layers grown by industrially relevant metalorganic vapor phase epitaxy on single crystalline Si. With the resulting improved understanding of defect formation on the atomic scale, strategies to avoid defects will be developed. In the first period of this project, we have established basic approaches to explain and largely suppress the formation of antiphase disorder in the GaP films. These UHV-based approaches will be further developed and improved for adaption to the growth process. For this purpose, electron microscopy studies will be performed under hitherto unrealized process-related conditions. The growth process can thereby be emulated at relevant precursor pressures while imaging the surface microscopically. The material system will be extended to application-relevant dilute-N-containing GaP-based multinary systems. The structural and chemical stability of the deposited materials under typical processing conditions and the bonding structure at the III-V/Si interface will be addressed utilizing mainly electron microscopy and reflection anisotropy spectroscopy.

• DFG Programme: Research Grants
• Co-Investigator: Dr. Gerhard Lilienkamp