Characterization of Ge nanocrystals in co-sputtered Ge+SiO2 system using Raman and TEM techniques

Wuiwui Chauhari Tjiu; S. P. Ng; W. K. Choi; V. Ng; Y. W. Ho

doi:10.1117/12.405383

24 October 2000 Characterization of Ge nanocrystals in co-sputtered Ge+SiO₂ system using Raman and TEM techniques

Wuiwui Chauhari Tjiu, S. P. Ng, W. K. Choi, V. Ng, Y. W. Ho

Proceedings Volume 4227, Advanced Microelectronic Processing Techniques; (2000) https://doi.org/10.1117/12.405383
Event: International Symposium on Microelectronics and Assembly, 2000, Singapore, Singapore

Abstract

In the present work, Ge nanocrystals were prepared by co- sputtering the Ge plus SIO₂ target in Argon at ambient temperature using a radio frequency (rf) magnetron sputterer. The nanocrystals were synthesized using the rapid thermal annealing technique. From the Raman experiments, a transition from amorphous to nanocrystalline Ge was found to occur at annealing temperature higher than 700 degrees C with a critical value of Ge concentration. The nanocrystals size was estimated to be 20 to 66 angstrom based on phonon confinement theory. The TEM results show that for sample annealed at 600 degrees C, both Ge clusters and small amount of nanocrystals are observed. For samples annealed at 800 degrees C, Ge nanocrystals are observed to be uniformly distributed in the silicon oxide matrix. They are almost spherical in shape with the spacing between the lattice fringes estimated to be 3 angstrom. For samples annealed at 900 and 1000 degrees C, a nanocluster/nanocrystals band was formed at the Si-SiO₂ interface. The TEM and Raman results agreed with each other for samples annealed at 600 and 800 degrees C. For samples annealed at 900 and 1000 degrees C, the Raman spectrum shows a rather broad band similar to amorphous Ge. However, TEM pictures for samples annealed at 900 and 1000 degrees C indicate the present of nanocrystals. We attribute the broadening of Raman peak of the 900 and 1000 degrees C annealed samples to the effect of size distribution and the formation of twin/dislocation structures.

Citation Download Citation

Wuiwui Chauhari Tjiu, S. P. Ng, W. K. Choi, V. Ng, and Y. W. Ho "Characterization of Ge nanocrystals in co-sputtered Ge+SiO₂ system using Raman and TEM techniques", Proc. SPIE 4227, Advanced Microelectronic Processing Techniques, (24 October 2000); https://doi.org/10.1117/12.405383

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