Surface activated Ge/GaAs wafer bonding for multi-junction solar cells

Author

Kono, Genki ; Fujino, Masahisa ; Yamashita, D. ; Watanabe, K. ; Sugiyama, Masakazu ; Nakano, Yoshiaki ; Suga, Takashi

Author_Institution

Dept. of Precision Eng., Univ. of Tokyo, Tokyo, Japan

fYear

2014

fDate

23-25 April 2014

Firstpage

720

Lastpage

723

Abstract

In this research, Ge/GaAs wafers were successfully bonded at room temperature by means of surface activated bonding (SAB) using fast atom beam (FAB) in high vacuum condition. Scanning acoustic microscope (SAM) observation shows wafers were bonded over almost the entire area. After 250°C annealing in N2 atomosphere, interfacial voids were reduced. Bonding strength of the interface archived 4.87MPa and most of fractured surface was GaAs. Transmission electron microscope (TEM) observation of bonding interface shows that Ge/GaAs were bonded at atomic level and amorphous layer with thickness of about 5nm was formed. Current-voltage (I-V) characteristic of directly bonded p-Ge/p-GaAs shows diode-like properties. The electrical resistance of bonded interface achieved 0.54Ωcm² at 0V and 0.16Ωcm² at 0.1V.

Keywords

gallium arsenide; germanium; scanning electron microscopy; solar cells; transmission electron microscopy; wafer bonding; FAB; Ge-GaAs; SAB; SAM; TEM; bonding interface; bonding strength; current-voltage characteristic; fast atom beam; multijunction solar cells; scanning acoustic microscope; surface activated bonding; transmission electron microscope; wafer bonding; Annealing; Bonding; Gallium arsenide; Microscopy; Photovoltaic cells; Resistance; Surface treatment; GaAs; Ge; Multi-jucntion solar cells; Surface activated bonding; Wafer dorect bpmdomg;

fLanguage

English

Publisher

ieee

Conference_Titel

Electronics Packaging (ICEP), 2014 International Conference on

Conference_Location

Toyama

Print_ISBN

978-4-904090-10-7

Type

conf

DOI

10.1109/ICEP.2014.6826774

Filename

6826774