Semiconductor Charge Carrier Control via Non-Uniform Doping
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Solution Overview
Problem
Conventional 3D imaging and time-of-flight sensors face inefficiencies in charge carrier transfer due to reliance on diffusion, leading to delayed and incomplete charge carrier collection at read-out nodes, especially with deeper penetration depths of infrared light.
Innovation Solution
A non-uniform doping profile is introduced in the semiconductor substrate to generate an electric field with vertical and lateral components, guiding photo-generated charge carriers efficiently towards accumulation regions using a control electrode structure with multiple electrodes, enabling faster and more effective charge carrier transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If diffusion-based charge carrier transfer is used, then device structure is simple, but charge carrier transfer speed is slow and transfer completeness is poor
Solution Approach 1:
The photo-conversion region is divided into multiple segments along the light propagation direction, with each segment containing control electrodes that independently control charge carrier transfer. This segmentation enables staged extraction of charge carriers at different depths, significantly improving transfer speed and completeness while maintaining manageable device complexity through modular architecture
Solution Approach 2:
Control electrodes are positioned above the photo-conversion region in a lateral dimension, creating electric fields that extend vertically into the photo-conversion region. This dimensional arrangement enables efficient charge carrier extraction from deep regions without requiring complex three-dimensional electrode structures within the substrate
2Illumination intensity
If deeper penetration depth of infrared light is achieved, then light sensitivity is improved, but charge carrier collection completeness deteriorates
Solution Approach 1:
Control electrodes are positioned and configured in advance above the photo-conversion region to create pre-established electric field pathways. These fields are ready to immediately guide and extract charge carriers generated at any depth, ensuring complete collection even from deeply penetrating infrared light without requiring complex post-generation manipulation
Solution Approach 2:
Electric fields generated by control electrodes serve as intermediary forces between photogenerated charge carriers and read-out nodes. These fields mediate the transport process, efficiently guiding carriers from deep penetration regions through the substrate to collection points, thereby maintaining high collection completeness despite increased light penetration depth
3Loss of time
If conventional diffusion-based transfer is used, then device operation is simple, but charge carrier transfer timing is delayed
Solution Approach 1:
Control electrodes are driven by time-varying signals that create periodic electric fields, enabling synchronized and timely extraction of charge carriers generated during different time intervals. This periodic control ensures accurate temporal resolution in time-of-flight measurements while maintaining manageable operational complexity through standardized signal driving
Solution Approach 2:
Electric fields are dynamically controlled through time-varying signals applied to control electrodes, allowing the system to adaptively guide charge carriers with precise temporal control. This dynamic field control enables fast and accurate charge carrier transfer timing while maintaining operational simplicity through electronic signal control rather than complex mechanical or structural adjustments
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the timely and complete transfer of charge carriers, improving the accuracy and efficiency of 3D imaging and depth sensing applications by reducing carrier loss and increasing the speed of charge carrier movement to read-out nodes.
Implementation Method 1
a photo-conversion region to convert light into photo-generated charge carriers
Implementation Method 2
providing a non-uniform doping profile such that an electric field with vertical field vector components is generated in at least a part of a photo-conversion region
Implementation Method 3
a control electrode structure including a plurality of control electrodes to generate a potential distribution such that the photo-generated carriers are guided towards the region to accumulate the photo-generated charge carriers based on signals applied to the control electrode structure
Data Source
AI summary
Embodiments related to controlling of photo-generated charge carriers are described and depicted. At least one embodiment provides a semiconductor substrate comprising a photo-conversion region to convert light into photo-generated charge carriers; a region to accumulate the photo-generated charge carriers; a control electrode structure including a plurality of control electrodes to generate a potential distribution such that the photo-generated carriers are guided towards the region to accumulate the photo-generated charge carriers based on signals applied to the control electrode structure; a non-uniform doping profile in the semiconductor substrate to generate an electric field with vertical field vector components in at least a part of the photo-conversion region.