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Study of Defects in Hydrogenated Amorphous Silicon by Constant Photocurrent Method and Positron Annihilation

Published online by Cambridge University Press:  17 March 2011

A. Amaral ,
G. Lavareda ,
C. Nunes de Carvalho ,
P. Brogueira ,
P. M. Gordo ,
V. S. Subrahmanyam ,
C. Lopes Gil ,
M.. Duarte Naia  and
A. P. de Lima
A. Amaral
Affiliation:
Centro de Física Molecular, Complexo Interdisciplinar I, IST/UTL, Av. Rovisco Pais, 1049-001 Lisboa, Portugal Departamento de Física, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa Codex, Portugal
G. Lavareda
Affiliation:
Centro de Física Molecular, Complexo Interdisciplinar I, IST/UTL, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
C. Nunes de Carvalho
Affiliation:
Centro de Física Molecular, Complexo Interdisciplinar I, IST/UTL, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
P. Brogueira
Affiliation:
Departamento de Física, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisboa Codex, Portugal
P. M. Gordo
Affiliation:
ICEMS, Departamento de Física, Universidade de Coimbra, Rua Larga da Universidade, 3004-516 Coimbra, Portugal
V. S. Subrahmanyam
Affiliation:
ICEMS, Departamento de Física, Universidade de Coimbra, Rua Larga da Universidade, 3004-516 Coimbra, Portugal
C. Lopes Gil
Affiliation:
ICEMS, Departamento de Física, Universidade de Coimbra, Rua Larga da Universidade, 3004-516 Coimbra, Portugal
M.. Duarte Naia
Affiliation:
Secção de Física da U.T.A.D., Quinta de Prados, Apartado 202, 5001-911 Vila Real, Portugal
A. P. de Lima
Affiliation:
ICEMS, Departamento de Física, Universidade de Coimbra, Rua Larga da Universidade, 3004-516 Coimbra, Portugal
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Abstract

The influence of the power density, PD, on the density and structure of defects of undoped a-Si:H thin films, deposited by rf-PECVD, is studied by constant photocurrent method, CPM, and by slow positron beam spectroscopy, respectively. Deep defect density, NDD, remains approximately constant at 10-16 cm-3, typical of device quality material, for PD in the range 7 - 20 mW.cm-3 calculated from CPM. NDD increases roughly one order of magnitude for both low and for high power densities. Positron annihilation spectroscopy reveals the presence of two kinds of vacancy type defects in the films: large vacancy clusters or voids for PD ∼ 7 mW.cm-3 and small vacancy type defects as PD increases to ∼30 mW.cm-3. The relative abundance of the structural defects is shown to be controlled by the power density used during the deposition without affect the electronic deep defect density, significantly.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 664: Symposium A – Amorphous and Heterogeneous Silicon-Based Films-2001 , 2001 , A22.5
Copyright
Copyright © Materials Research Society 2001

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References

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