This broadband photodetector offers enhanced sensitivity, responsivity, and stability operating over a wide range of light wavelengths—from near-ultraviolet to near-infrared—at low power consumption.
Georgia Tech’s innovation has a 3D photodiode structure that features a specially designed textured top electrode with nanowire arrays to maximize light absorption. A conformal alumina layer is inserted between two constituent semiconductors of a p-n junction to form dual inversion layers. This unique structure leads to significant enhancement of photo-excited charge carrier separation and collection efficiency. The photo-sensing responsivity and sensitivity are nearly one order of magnitude higher than that of a reference device of p-Si/N-ZnO nanowire arrays.
This innovation potentially paves the way for a practical and efficient approach to converting light to electricity, resulting in high-performance broadband photodetectors and other optoelectronics.
- Enhanced sensitivity: Functions over a wide range of wavelengths—from near-ultraviolet to near-infrared
- High performance: Operates at high-speed response conditions in wide spectral bandwidth for various applications
- High stability and repeatability: Offers significant photo-sensing ability with no deviation or degradation observed after one year
- 3D structure: Leverages superior properties of nanowires—high surface area, longer optical paths, wider acceptance angles, and low surface reflection—to increase sensitivity and enhance electrode transmission
- Low power consumption: Operates at a negative bias of only -2 volts, with high output values
- Optical-fiber communications systems
- Medical imaging
- Thermal imaging
- Environmental monitoring
- Defense technology
Though silicon photonics have revolutionized numerous applications in communications, biomedical diagnostics, and more, silicon possesses many shortcomings as a photonic material. For example, its indirect energy band and highly reflective surface limit light absorption. And when incident optical power increases, silicon photonic devices reach a saturation limit and responsivity decreases significantly.
Georgia Tech’s innovation employs a unique 3D structure with a textured top electrode that works as an anti-reflection layer to improve light absorption. This structure also takes advantage of the superior properties of nanowires to enhance electrode transmission and increase broadband photo-sensing.