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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Optimization of Ohmic Contacts to p-GaAs Nanowires

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Piton, Marcelo Rizzo [1, 2] ; Hakkarainen, Teemu [2] ; Hilska, Joonas [2] ; Koivusalo, Eero [2] ; Lupo, Donald [3] ; Avanco Galeti, Helder Vinicius [4] ; Gobato, Yara Galvao [1] ; Guina, Mircea [2]
Total Authors: 8
[1] Univ Fed Sao Carlos, Phys Dept, Sao Carlos, SP - Brazil
[2] Tampere Univ, Phys Unit, Optoelect Res Ctr, Tampere - Finland
[3] Tampere Univ, Elect & Commun Engn, Tampere - Finland
[4] Univ Fed Sao Carlos, Elect Engn Dept, Sao Carlos, SP - Brazil
Total Affiliations: 4
Document type: Journal article
Source: NANOSCALE RESEARCH LETTERS; v. 14, n. 1 DEC 2019.
Web of Science Citations: 0

The performance of Ohmic contacts applied to semiconductor nanowires (NWs) is an important aspect for enabling their use in electronic or optoelectronic devices. Due to the small dimensions and specific surface orientation of NWs, the standard processing technology widely developed for planar heterostructures cannot be directly applied. Here, we report on the fabrication and optimization of Pt/Ti/Pt/Au Ohmic contacts for p-type GaAs nanowires grown by molecular beam epitaxy. The devices were characterized by current-voltage (IV) measurements. The linearity of the IV characteristics curves of individual nanowires was optimized by adjusting the layout of the contact metal layers, the surface treatment prior to metal evaporation, and post-processing thermal annealing. Our results reveal that the contact resistance is remarkably decreased when a Pt layer is deposited on the GaAs nanowire prior to the traditional Ti/Pt/Au multilayer layout used for p-type planar GaAs. These findings are explained by an improved quality of the metal-GaAs interface, which was evidenced by grazing incidence X-ray diffraction measurements in similar metallic thin films deposited on GaAs (110) substrates. In particular, we show that Ti exhibits low degree of crystallinity when deposited on GaAs (110) surface which directly affects the contact resistance of the NW devices. The deposition of a thin Pt layer on the NWs prior to Ti/Pt/Au results in a 95% decrease in the total electrical resistance of Be-doped GaAs NWs which is associated to the higher degree of crystallinity of Pt than Ti when deposited directly on GaAs (110). (AU)

FAPESP's process: 14/50513-7 - Tailoring the transport and optical properties if III-Bi-V nanostructures for advanced photonic devices
Grantee:Helder Vinícius Avanço Galeti
Support type: Regular Research Grants
FAPESP's process: 16/10668-7 - Optical and Transport Properties of two-dimensional semicondutors based on transition metal dichalcogenides
Grantee:Yara Galvão Gobato
Support type: Regular Research Grants