Open AccessGe/Si heterojunction photodiodes fabricated by low temperature wafer bonding
Author(s) -
Farzan Gity,
Aidan Daly,
Bradley Snyder,
Frank Peters,
John M. Hayes,
Cindy Colinge,
Alan P. Morrison,
Brian Corbett
Publication year - 2013
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.21.017309
Subject(s) - materials science , responsivity , photodiode , heterojunction , optoelectronics , wafer , dark current , wafer bonding , depletion region , capacitance , photodetector , silicon , optics , semiconductor , electrode , chemistry , physics
We report on the photoresponse of an asymmetrically doped p(-)-Ge/n(+)-Si heterojunction photodiode fabricated by wafer bonding. Responsivities in excess of 1 A/W at 1.55 μm are measured with a 5.4 μm thick Ge layer under surface-normal illumination. Capacitance-voltage measurements show that the interfacial band structure is dependent on both temperature and light level, moving from depletion of holes at -50 °C to accumulation at 20 °C. Interface traps filled by photo-generated and thermally-generated carriers are shown to play a crucial role. Their filling alters the potential barrier height at the interface leading to increased flow of dark current and the above unity responsivity.