Identification of Vibrational Modes in BaSi₂ Epitaxial Films by Infrared and Raman Spectroscopy

Abstract:

Infrared (IR) absorption and polarized Raman spectra were measured in BaSi₂ epitaxial films to investigate the vibrational modes and the symmetry of Si₄ cluster in BaSi₂. By an analysis based on Raman and/or IR activity in the spectra, the symmetry of Si₄ cluster was determined as T_h-symmetry and the observed Raman lines and IR peaks were assigned to A_g, E_g, F_g, and F_u, respectively. In the three Raman lines of F_g-mode, one LO phonon line and two TO phonon lines were classified by the depolarization ratio of polarized Raman intensities.

• Periodical: Defect and Diffusion Forum (Volume 386)
• Pages: 43-47
• DOI: https://doi.org/10.4028/www.scientific.net/DDF.386.43
• Online since: September 2018
• Authors: Hirofumi Hoshida, Naoki Murakoso, Takashi Suemasu, Yoshikazu Terai*
• Keywords: BaSi₂, Epitaxial Film, Infrared Spectroscopy, Polarized Raman Spectroscopy, Semiconducting Silicide

References

[1] T. Suemasu, N. Usami, Exploring the potential of semiconducting BaSi2 for thin-film solar cell applications, J. Phys. D: Appl. Phys. 50 (2017) 023001(1-18).

DOI: 10.1088/1361-6463/50/2/023001

[2] K. Toh, T. Saito, T. Suemasu, Optical Absorption Properties of BaSi2 Epitaxial Films Grown on a Transparent Silicon-on-Insulator Substrate Using Molecular Beam Epitaxy, Jpn. J. Appl. Phys. 50 (2011) 068001(1-2).

DOI: 10.7567/jjap.50.068001

[3] M. Baba, K. Toh, K. Toko, N. Saito, N. Yoshizawa, K. Jiptner, T. Sakiguchi, K. O. Hara, N. Usami, T. Suemasu, Investigation of grain boundaries in BaSi2 epitaxial films on Si(111) substrates using transmission electron microscopy and electron-beam-induced current technique, J. Cryst. Growth 348 (2012).

DOI: 10.1016/j.jcrysgro.2012.03.044

[4] R. Takabe, K. O. Hara, M. Baba, W. Du, N. Shimada, K. Toko, N. Usami, T. Suemasu, Influence of grain size and surface condition on minority-carrier lifetime in undoped n-BaSi2 on Si(111), J. Appl. Phys. 115 (2014) 193510(1-7).

DOI: 10.1063/1.4878159

[5] D. Tsukahara, S. Yachi, H. Takeuchi, R. Takabe, W. Du, M. Baba, Y. Li, K. Toko, N. Usami, T. Suemasu, p-BaSi2/n-Si heterojunction solar cells with conversion efficiency reaching 9.0%, Appl. Phys. Lett. 108 (2016) 152101(1-5).

DOI: 10.1063/1.4945725

[6] S. Yachi, R. Takabe, H. Takeuchi, K. Toko, T. Suemasu, Effect of amorphous Si capping layer on the hole transport properties of BaSi2 and improved conversion efficiency approaching 10% in p-BaSi2/n-Si solar cells, Appl. Phys. Lett. 109 (2016).

DOI: 10.1063/1.4961309

[7] K. Kodama, R. Takabe, T. Deng, K. Toko, T. Suemasu, Spectroscopic evidence of photogenerated carrier separation by built-in electric field in Sb-doped n-BaSi2/B-doped p-BaSi2 homojunction diodes, Jpn. J. Appl. Phys. 57 (2018) 050310(1-3).

DOI: 10.7567/jjap.57.050310

[8] M. Baba, K. Watanabe, K. O. Hara, K. Toko, T. Sekiguchi, N. Usami, T. Suemasu, Evaluation of minority carrier diffusion length of undoped n-BaSi2 epitaxial thin films on Si(001) substrates by electron-beam-induced-current technique, Jpn. J. Appl. Phys. 53 (2014).

DOI: 10.7567/jjap.53.078004

[9] K. Toh, K. O. Hara, N. Usami, N. Saito, N. Yoshizawa, K. Toko, T. Suemasu, Molecular beam epitaxy of BaSi2 thin films on Si(001) substrates, J. Cryst. Growth 345 (2012) 16-21.

DOI: 10.1016/j.jcrysgro.2012.01.049

[10] Y. Inomata, T. Nakamura, T. Suemasu, F. Hasegawa, Epitaxial Growth of Semiconducting BaSi2 Films on Si(111) Substrates by Molecular Beam Epitaxy, Jpn. J. Appl. Phys. 43 (2004) 478-481.

DOI: 10.1143/jjap.43.l478

[11] M. Nakayama, K. Kubota, T. Kanata, H. Kato, S. Chika, N. Sano, Raman study of GaAs‐InxAl1−x As strained‐layer superlattices, J. Appl. Phys. 58 (1985) 4342-4345.

DOI: 10.1063/1.335522

[12] Y. Terai, H. Yamaguchi, H. Tsukamoto, N. Murakoso, M. Iinuma, T. Suemasu, Polarized Raman spectra of BaSi2 epitaxial film grown by molecular beam epitaxy, Jpn. J. Appl. Phys. 56 (2017) 05DD02(1-4).

DOI: 10.7567/jjap.56.05dd02

[13] M. Somer, Vibrational Spectra of the Cluster Anions [E4]4– in the metallic Sodium and Barium Compounds Na4E4 and Ba2E4 (E = Si, Ge), Z. Anorg. Allg. Chem. 626 (2000) 2478-2480.

DOI: 10.1002/1521-3749(200012)626:12<2478::aid-zaac2478>3.0.co;2-a

[14] M. Kumar, N. Umezawa, W. Zhou, M. Imai, Barium disilicide as a promising thin-film photovoltaic absorber: structural, electronic, and defect properties, J. Mater. Chem. A 5 (2017) 25293-25302.

DOI: 10.1039/c7ta08312b

[15] D. L. Rousseau, R. P. Bauman, S. P. S. Porto, Normal mode determination in crystals, J. Raman Spectrosc. 10 (1981) 253-290.

DOI: 10.1002/jrs.1250100152

[16] W. Hayes and R. Loudon, Scattering of Light by Crystals, (Dover Publications), New York, (2004) pp.112-117.