Ge/Si heterojunction photodiodes fabricated by low temperature wafer bonding.
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.
Tyndall National Institute, Lee Maltings, Dyke Parade, Cork, Ireland. Farzan.Gity@Tyndall.ie
Farzan
F
Gity
Aidan
A
Daly
Bradley
B
Snyder
Frank H
FH
Peters
John
J
Hayes
Cindy
C
Colinge
Alan P
AP
Morrison
Brian
B
Corbett
D003460:Crystallization / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005857:Germanium / Q000737:chemistry* / Q000528:radiation effects; D008422:Materials Testing; D010783:Photometry / Q000295:instrumentation*; D012666:Semiconductors; D012825:Silicon / Q000737:chemistry* / Q000528:radiation effects; D013696:Temperature
D005857:Germanium; D012825:Silicon