Improved Near-infrared Photoresponse of Si-based Schottky Diode by Nanophotonic Structures

Schottky photodetectors based on internal photoemission enable the detection of infrared radiation beyond the spectral range of silicon pin diodes. Major drawbacks for many applications are the low quantum efficiency and the dark current. Among all approaches to solving these issues, this work focuses on nanophotonic structures to reduce the reflection of the device. We present a backside-illuminated AlSiCu/Si Schottky photodetector with nanopyramids in various sizes produced with a full CMOS compatible process. We found a Schottky barrier height of 0.59 eV while keeping dark current density low (under $1 A\cdot m^{-2}$ at 293 K) and we were able to show an improvement in optical responsivity by a factor of more than seven within the wavelength range from 1300 nm to 1600 nm compared to planar devices.