Infrared Detector Transparent Common Ground Structure
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Solution Overview
Problem
Existing infrared detector devices face challenges in maximizing quantum efficiency due to in-band photon absorption in the contact layer and insufficient electrical conductivity for common grounding in focal plane arrays, leading to systematic quantum efficiency loss.
Innovation Solution
A wider bandgap contact design that is transparent to specific infrared bands, serving as both a common ground and etch stop structure, allowing full pixel reticulation with minimal erosion, and incorporating a common ground structure with a bandgap wider than the detector structure to enhance quantum efficiency and conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a frontside contact layer is used to maximize quantum efficiency, then proximity of photo generated carriers to the contact is improved, but in-band photon absorption in the contact layer causes systematic quantum efficiency loss
Solution Approach 1:
The patent extracts the contact function from the frontside and relocates it to the backside of the detector. The backside contact layer serves as the common ground contact, separating the illumination function (frontside) from the electrical contact function (backside). This eliminates in-band photon absorption in the frontside contact while maintaining electrical connectivity through the backside contact structure.
Solution Approach 2:
The patent inverts the conventional contact configuration by placing the common ground contact on the backside of the detector rather than on the frontside. This inversion allows illumination to occur through the frontside without interference from contact layer absorption, while the backside contact provides the necessary electrical grounding function.
2Measurement precision
If a frontside contact layer is used for illumination, then quantum efficiency is maximized, but the contact layer does not provide enough electrical conductivity to serve as common grounding layer
Solution Approach 1:
The patent extracts the electrical contact function from the frontside illumination path and places it on the backside. The backside contact layer is designed with sufficient thickness and doping to provide the necessary electrical conductivity for common grounding, while the frontside remains optimized for illumination without contact layer interference.
Solution Approach 2:
The patent transitions the contact function to another dimension (backside) rather than attempting to fulfill both illumination and electrical contact functions in the same frontside layer. This dimensional separation allows each function to be optimized independently - frontside for illumination transparency and backside for electrical conductivity.
3Reliability
If a common ground structure is made opaque to ensure electrical conductivity, then grounding is sufficient, but radiation absorption is blocked
Solution Approach 1:
The patent extracts the common ground structure from the illumination path by placing it on the backside of the detector. The backside contact layer provides the necessary electrical conductivity for grounding without interfering with frontside illumination. The structure is designed to be transparent to incident radiation while maintaining electrical functionality.
Solution Approach 2:
The patent inverts the conventional placement of the common ground structure from the frontside to the backside. This inversion allows the ground structure to provide sufficient electrical conductivity without blocking incident radiation, as the illumination path through the frontside is kept separate from the backside contact structure.
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 solution improves quantum efficiency and provides sufficient electrical conductivity for focal plane arrays, enabling effective radiation absorption and signal collection while maintaining the integrity of the common ground structure, thus enhancing the performance of infrared detector devices.
Implementation Method 1
The common ground structure has a bandgap that is wider than a bandgap of the detector structure and is transmissive to radiation having a wavelength in a predetermined spectral band
Implementation Method 2
The detector structure is capable of absorbing radiation
Data Source
AI summary
Focal plane arrays and infrared detector device having a transparent common ground structure and methods of their fabrication are disclosed. In one embodiment, a front-side illuminated infrared detector device includes a contact layer and a detector structure adjacent to the contact layer. The detector structure is capable of absorbing radiation. The front-side illuminated infrared detector device further includes a common ground structure adjacent the detector structure, wherein the common ground structure is transmissive to radiation having a wavelength in a predetermined spectral band, and the common ground structure has a bandgap that is wider than a bandgap of the detector structure. The front-side illuminated infrared detector device further includes an optical layer adjacent the common ground structure.