Heterojunction Image Sensor for Selective IR Charge Transfer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing solid-state imaging devices face challenges in efficiently converting near-infrared or short-wave infrared light into charge carriers and achieving appropriate selective transfer of charge carriers due to interference from external light and large-capacitance capacitors.
Innovation Solution
A solid-state image sensor is designed with a first semiconductor composed of Ge or Ge-based compounds for efficient light absorption, and a second semiconductor for signal processing, featuring transfer controllers and carrier storages that enable selective transfer of charge carriers without large-capacitance capacitors, using a heterojunction structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If germanium or Ge-based compounds are used for light absorption, then light conversion efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The image sensor is divided into two distinct semiconductor regions: a first semiconductor region containing the photodiode for light absorption, and a second semiconductor region for charge carrier processing. This segmentation allows each region to be optimized independently, with the first region using Ge-based materials for high light conversion efficiency while the second region can use more manufacturable materials.
Solution Approach 2:
The patent employs a composite semiconductor structure combining different semiconductor materials with complementary properties. The first semiconductor uses Ge or Ge-based compounds for superior infrared light absorption, while the second semiconductor provides compatible electrical characteristics for charge carrier transfer and storage, creating a heterogeneous structure that optimizes both light conversion and signal processing.
2Reliability
If large-capacitance capacitors are used for charge carrier storage, then noise reduction is improved, but device area increases
Solution Approach 1:
The patent extracts and eliminates the large-capacitance capacitor component from the charge carrier storage system. Instead of using traditional capacitor-based storage that requires large area, the invention uses the inherent charge carrier storage capability of the semiconductor material itself, achieved through controlled potential wells and electric field management in the second semiconductor region.
Solution Approach 2:
The patent replaces the mechanical/electrical capacitor structure with a semiconductor-based electric field control mechanism. Charge carriers are stored and managed through controlled potential distributions and electric fields within the semiconductor material, eliminating the need for physical capacitor structures and their associated area requirements.
3Measurement precision
If selective charge carrier transfer is implemented, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent combines the charge carrier transfer control function with the semiconductor structure itself. The heterojunction between the first and second semiconductor regions creates natural potential barriers and channels that guide charge carrier transfer, merging the transfer control mechanism with the material structure rather than requiring separate control components.
Solution Approach 2:
The semiconductor heterojunction structure provides self-directed charge carrier transfer through built-in electric fields and potential gradients. The material structure itself performs the selective transfer function based on the applied voltages, without requiring complex external control mechanisms, achieving selective transfer through the inherent properties of the heterostructure.
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
The sensor effectively operates with near-infrared or short-wave infrared light, achieving efficient conversion and appropriate selective carrier transfer, enabling distance measurement with reduced noise and improved signal-to-noise ratio.
Implementation Method 1
a photodiode that converts light incident on the photodiode into charge carriers
Implementation Method 2
a first semiconductor having a first composition and including a photodiode that converts light incident on the photodiode into charge carriers
Data Source
AI summary
A solid-state image sensor includes a first semiconductor, and a second semiconductor having a composition different from that of the first composition and electrically connected to the first semiconductor. The first semiconductor includes a photodiode that converts light incident on the photodiode into charge carriers, first carrier storages that store the charge carriers, and a transfer gate that controls transfer the charge carriers to a selected one of the first carrier storages. The second semiconductor includes second carrier storages and a potential detection node. The second carrier storages each store charge carriers based on the charge carriers stored in a corresponding one of the first carrier storages. The potential detection node detects the electric potential of each of the second carrier storages. The solid-state image sensor further includes a reset transistor that resets the electric potential of each of the first carrier storages to a predetermined electric potential.