화학공학소재연구정보센터
Thin Solid Films, Vol.455-56, 217-221, 2004
Optical constants and interband transitions of Ge1-xSnx alloys (x < 0.2) grown on Si by UHV-CVD
The development of manufacturable direct band gap materials on Si is crucial for optoclectronic devices integrated with silicon circuits. Ge-Sn alloys with varying metastable compositions ranging from 2 to 20% were grown by UHV-CVD using a deuterium-stabilized Sn hydride with digermane. We use deep ultraviolet spectroscopic ellipsometry (0.74 to 6.6 eV) to determine the optical properties of this new class of Si-based infrared semiconductors in the Ge-1 -Sn-x(x) system. Optical analysis of the energy-derivatives in comparison with analytical lineshapes shows that the E-1 and E-2 interband transition energies decrease significantly with increasing Sn content. Tunability of these high-energy gaps shows promise for a direct E-0 band gap in this materials system. (C) 2003 Elsevier B.V. All rights reserved.