Graded GeSi Optical Sensor for Near-Infrared Detection

The patent employs a composite material structure consisting of a silicon substrate combined with a germanium layer. The silicon portion provides compatibility with existing CMOS manufacturing processes, while the germanium layer enhances near-infrared optical absorption efficiency. This composite approach allows the sensor to maintain ease of manufacture through standard silicon processing while achieving superior NIR detection performance that pure silicon cannot provide.

The patent divides the sensor structure into distinct functional segments: a silicon-based photodetector region and a separate germanium layer optimized for near-infrared absorption. This segmentation allows each material to perform its optimal function while minimizing drawbacks - the silicon region generates minimal dark current, while the germanium layer provides enhanced NIR absorption. The layered architecture enables the system to achieve high sensitivity without proportionally increasing dark current noise.

The patent optimizes the thickness parameter of the germanium layer to achieve maximum near-infrared absorption while minimizing carrier recombination losses. By carefully controlling the germanium layer thickness (typically in the range of micrometers), the structure absorbs sufficient NIR photons to generate strong photocurrent signals while maintaining a thickness that prevents excessive carrier recombination. This parameter optimization allows the sensor to achieve high sensitivity without the penalty of increased recombination that would occur with much thicker layers.