Doctoral theses of the School of Electrical Engineering are available in the open access repository maintained by Aalto, Aaltodoc.
Public defence in Photonics and Nanotechnology, M.Sc.(Tech.) Olli Setälä
Public defence from the Aalto University School of Electrical Engineering, Department of Electronics and Nanoengineering
The title of the thesis: Enhanced photodiode performance via surface nanoengineering
Thesis defender: Olli Setälä
Opponent: Dr. Jesper Skottfelt, Open University, United Kingdom
Custos: Prof. Hele Savin, Aalto University School of Electrical Engineering
The demand for efficient detection of light signals has recently seen a rapid increase due to developments in fields, such as autonomous vehicles and wearable health monitoring technologies. Silicon-based photodiodes are currently the most common devices used for photodetection. However, their detection efficiency has traditionally been limited by surface reflectance and electrical losses, which cause portion of the light not being detected.
In this dissertation, these deficiencies are mitigated by applying recent surface nanoengineering methods to silicon photodiodes and related devices such as image sensors and particle detectors. The approaches include nanostructuring of the detector surface and coating the device with atomic layer deposited thin films, which can solve the reflectance and electrical loss problems, respectively. The resulting devices surpass the performance of the state-of-the-art silicon detectors and achieve near ideal efficiencies demonstrating the potential of surface nanoengineering in a multitude of applications. Improved performance could for instance allow more sensitive LiDAR systems, improved imaging performance with digital cameras, detection of faint astronomical objects, more effective night vision cameras and miniaturization of sensors. The results demonstrate that ~100% detection efficiency can be reached with only minor modifications to the traditional photodiode designs. Importantly, integration of the surface nanoengineering techniques to the existing conventional processing lines is easy providing a simple route for their direct application to commercial devices.
Key words: photodiode, black silicon, atomic layer deposition, quantum efficiency
Thesis available for public display 7 days prior to the defence at .
Contact: olli.setala@aalto.fi
Doctoral theses of the School of Electrical Engineering
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