Title :
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
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;
Conference_Titel :
Electronics Packaging (ICEP), 2014 International Conference on
Conference_Location :
Toyama
Print_ISBN :
978-4-904090-10-7
DOI :
10.1109/ICEP.2014.6826774
