Image Sensor Adhesion Buffer Layer for X-Ray Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Direct conversion-type image sensors face issues with poor adhesion of photoconductive layers made from high atomic weight semiconductor materials to aluminum or copper front electrodes, leading to instability and potential detachment.
Innovation Solution
A buffer layer with higher adhesion strength, composed of materials like CdS or ZnTe, is interposed between the photoconductive layer and the aluminum or copper front electrode, enhancing the adhesion and stability of the photoconductive layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a photoconductive layer made from high atomic weight semiconductor materials (CdTe, CdZnTe, PbO, etc.) is directly formed on an aluminum or copper front electrode, then the image sensor achieves direct conversion capability and high resolution, but the adhesion strength between the photoconductive layer and front electrode deteriorates, causing the photoconductive layer to come loose
Solution Approach 1:
A buffer layer is introduced as an intermediary between the front electrode (aluminum or copper) and the photoconductive layer (CdTe, CdZnTe, PbO, etc.). This buffer layer serves as a mediator that provides strong adhesion to both the metal electrode and the semiconductor photoconductive material, resolving the adhesion problem while maintaining the direct conversion capability and high resolution of the image sensor.
Solution Approach 2:
The buffer layer is formed using composite material structures, specifically utilizing materials like CdS or ZnTe that exhibit strong adhesion properties to both aluminum/copper electrodes and high atomic weight semiconductor photoconductive materials. This composite approach combines the advantages of different materials to achieve both strong adhesion and photoconductive functionality.
2Device complexity
If a photoconductive layer made from high atomic weight semiconductor materials is directly formed on an aluminum or copper front electrode, then the device structure remains simple, but the reliability deteriorates due to poor adhesion and potential detachment
Solution Approach 1:
The buffer layer acts as a reliable intermediary that ensures stable adhesion between the front electrode and photoconductive layer. By introducing this intermediate layer with specific adhesion properties, the overall reliability of the device is enhanced without significantly complicating the structure, as the buffer layer integrates seamlessly into the existing layer architecture.
Solution Approach 2:
The buffer layer provides beforehand cushioning by preemptively addressing the adhesion problem before the photoconductive layer is formed. This preventive measure ensures that the photoconductive layer will not detach during subsequent processing or device operation, thereby improving reliability in advance.
Data Source
AI summary
Disclosed is an image sensor, which is characterized by increased strength of adhesion between a photoconductive layer and a front electrode made of aluminum, and which includes a first electrode composed of aluminum, copper or an aluminum-copper alloy on a substrate, a buffer layer formed on the first electrode, a photoconductive layer formed on the buffer layer, and a second electrode formed on the photoconductive layer, wherein the buffer layer includes a material having higher strength of adhesion than the photoconductive layer to the first electrode.