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Silicon-germanium films deposited by low-frequency plasma-enhanced chemical vapor deposition: Effect of H2 and Ar dilution

Published online by Cambridge University Press:  01 January 2006

A. Kosarev ,
A. Torres ,
Y. Hernandez ,
R. Ambrosio ,
C. Zuniga ,
T.E. Felter ,
R. Asomoza ,
Y. Kudriavtsev ,
R. Silva-Gonzalez  and
E. Gomez-Barojas
...Show all authors
A. Kosarev*
Affiliation:
Institute National for Astrophysics, Optics and Electronics, INAOE, CP 7200, Puebla, Mexico
A. Torres
Affiliation:
Institute National for Astrophysics, Optics and Electronics, INAOE, CP 7200, Puebla, Mexico
Y. Hernandez
Affiliation:
Institute National for Astrophysics, Optics and Electronics, INAOE, CP 7200, Puebla, Mexico
R. Ambrosio
Affiliation:
Institute National for Astrophysics, Optics and Electronics, INAOE, CP 7200, Puebla, Mexico
C. Zuniga
Affiliation:
Institute National for Astrophysics, Optics and Electronics, INAOE, CP 7200, Puebla, Mexico
T.E. Felter
Affiliation:
Lawrence Livermore National Laboratory, Livermore, California 94550
R. Asomoza
Affiliation:
Centro de Investigación y de Estudios Avanzado del Instituto Politecnico Nacional, Mexico, D.F. 07360
Y. Kudriavtsev
Affiliation:
Centro de Investigación y de Estudios Avanzado del Instituto Politecnico Nacional, Mexico, D.F. 07360
R. Silva-Gonzalez
Affiliation:
Instituto de Fisica, Benemerita Universidad Autonoma de Puebla, Puebla, Pue., C.P. 72570, Mexico
E. Gomez-Barojas
Affiliation:
CIDS-IC, Benemerita Universidad Autonoma de Puebla, Puebla, Pue. C.P. 72000, Mexico
A. Ilinski
Affiliation:
Benemerita Universidad Autonoma de Puebla, Puebla, Puebla 72050, Mexico
A.S. Abramov
Affiliation:
A.F. Ioffe Phys.-Technical Institute, St.-Petersburg 194021, Russia
*
a)Address all correspondence to this author. e-mail: akosarev@inaoep.mx
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Abstract

We have studied structure and electrical properties of Si1−YGeY:H films deposited by low-frequency plasma-enhanced chemical vapor deposition over the entire composition range from Y = 0 to Y = 1. The deposition rate of the films and their structural and electrical properties were measured for various ratios of the germane/silane feed gases and with and without dilution by Ar and by H2. Structure and composition was studied by Auger electron spectroscopy (AES), secondary ion mass spectroscopy (SIMS), and Fourier transform infrared (FTIR) spectroscopy. Surface morphology was characterized by atomic force microscopy (AFM). We found that the deposition rate increased with Y, maximizing at Y = 1 without dilution. The relative rate of Ge and Si incorporation is affected by dilution. Hydrogen preferentially bonds to silicon. Hydrogen content decreases for increasing Y. In addition, optical measurements showed that as Y goes for 0 to 1, the Fermi level moves from mid gap to the conduction band edge; i.e., the films become more n-type. No correlation was found between the pre-exponential and the activation energy of conductivity. The behavior of the conductivity γ-factor suggests a local minimum in the density of states at E ≈ 0.33 eV for the films grown with or without H-dilution and E ≈ 0.25 eV for the films with Ar dilution.

Keywords

AmorphousElectronic materialPlasma-enhanced CVD (PECVD)
Type
Articles
Information
Journal of Materials Research , Volume 21 , Issue 1 , January 2006 , pp. 88 - 104
Copyright
Copyright © Materials Research Society 2006

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