HOLE-DIFFUSION LENGTH AND TRANSPORT PARAMETERS OF THIN CDS FILMS FROM A SCHOTTKY BARRIER

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HOLE-DIFFUSION LENGTH AND TRANSPORT PARAMETERS OF THIN CDS FILMS FROM A

SCHOTTKY BARRIER

J. Ebothe

To cite this version:

J. Ebothe. HOLE-DIFFUSION LENGTH AND TRANSPORT PARAMETERS OF THIN CDS

FILMS FROM A SCHOTTKY BARRIER. Journal de Physique Colloques, 1989, 50 (C6), pp.C6-

176-C6-176. �10.1051/jphyscol:1989630�. �jpa-00229661�

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R E W E DE PHYSIQUE APPLIQUEE

Colloque C6, Supplt5ment au n06, Tome 24, Juin 1989

HOLE-DIFFUSION LENGTH AND TRANSPORT PARAMETERS OF THIN CDS FILMS FROM A SCHOTTKY BARRIER

J. EBOTHE

Institut Lebel, Universit6 Louis Pasteur, 4, rue Blaise Pascal, F-67000 Strasbourg, France

The minority carrier diffusion length of semiconductor thin films in polycrystalline form is determined with a good precision by EBIC and LBIC techniques ( I 2 )

.

The electron or laser beam used is scan- ned across the junction. The principle applied in these cases might be attractive for the semiconducting hand side of liquid Schottky bar- riers. However, these techniques cannot be easily used for such junc- tions. The methods based on the Gardner approach ( 3 ) remain so far more convenient here, especially when very thin films are concerned. In this context, two independent techniques, namely, the surface photovoltage

( SPV) ( 4 ) and the photoelectrochemical ( 5 ) measurements served in this work.

The optoelectronic and transport properties of thin sprayed CdS films, having a thickness of less than 2 ym are reported ( 6 ) . The two techniques used led to a good agreement in the hole-diffusion length values. These range from 0 . 0 1 7 to 0 . 1 5 ym and behaved differently in two zones. A rapid increase of this parameter is observed below a film thickness of 0 , 4 ym. Above this thickness, the value obtained is constant Specific space-charge widths are expected because of the respective measurement conditions. The hole-diffusion length decreases as carrier density increases. The hole lifetime shows a regular decreases as the thickness factor increases, while the hole-diffusion coefficient and mobility patterns are similar to that of the photocurrent.

References

*

( 1 ) J.J. OAKES, I.G. GREENFIELD and L.D. PARTAIN, J. Appl. Phys., 4 8 ,

2 5 4 8 ( 1 9 7 7 )

( 2 ) J.E. MAHAN, T.W. EKSTEDT, R.I. FRANK and R. KAPLOW, IEEE, Trans.

Electron Dev. ED-26, 7 3 3 ( 1 9 7 9 ) ( 3 ) W.W. GARTNER, Phys. Rev. 8 4 ( 1 9 5 9 )

( 4 ) B.L. WHEELER, G. NAGASUBRAMANIAN and J. BARD, J. Electrochem. Soc.

1 3 1 , 1 0 3 8 ( 1 9 8 4 )

(5) P. SALVADOR, J. Appl. Phys. 55, 2 9 7 7 ( 1 9 8 4 ) ( 6 ) J

.

^EBOTHE, J

.

&pl.Phys. 59, 2076 (1 986)

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1989630