Application of δ-doping in GaAs tunnel junctions

Author

Ragay, F.W. ; Leys, M.R. ; Wolter, J.H.

Author_Institution

Dept. of Appl. Phys., Eindhoven Univ. of Technol., Netherlands

Volume

30

Issue

1

fYear

1994

fDate

1/6/1994 12:00:00 AM

Firstpage

86

Lastpage

87

Abstract

The technique of δ-doping has been employed to fabricate MBE grown GaAs tunnel junctions for application as intercell contacts in tandem solar cells. By applying δ-doping, the effective Si concentration can be increased by almost a factor 10. In this way an effective n-type doping level of ~2×10¹⁹cm^-3 can be obtained. By growth at low temperature a p-type concentration of 2×10¹⁹cm^-3 can be achieved using Be. The as-grown δ-doped tunnel junction showed a tunnel current of 55Acm ^-2. A tunnel diode with homogeneous Si doping of 4 × 10 ¹⁸cm^-3 shows a much lower tunnel current of 1.3mAcm^-2. To simulate the growth of the top cell, the tunnel junction was annealed at 650°C for 2h. After annealing the peak current of the δ-doped tunnel junction dropped to 183mAcm^-2. This is still sufficient for forming intercell contacts in GaAs-AlGaAs tandem cells

Keywords

III-V semiconductors; annealing; doping profiles; gallium arsenide; semiconductor doping; solar cells; tunnel diodes; δ-doping; GaAs tunnel junctions; GaAs-AlGaAs; GaAs-AlGaAs tandem cells; GaAs:Be; GaAs:Si; I-V characteristics; MBE; Si concentration; annealing; heavily doped regions; homogeneous Si doping; intercell contacts; n-type doping level; p-type concentration; peak current; tandem solar cells; tunnel current; tunnel diode;

fLanguage

English

Journal_Title

Electronics Letters

Publisher

iet

ISSN

0013-5194

Type

jour

DOI

10.1049/el:19940002

Filename

260620