Photosensitive IC Reflective Layer Quantum Efficacy
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Solution Overview
Problem
The existing production methods for photosensitive microchips, particularly those using photodiodes, suffer from reduced quantum efficacy due to unabsorbed photons being lost as they are either reflected or refracted into intermetallic levels of the integrated circuit, rather than being absorbed and converted into electron-hole pairs.
Innovation Solution
A reflective layer, made from materials like titanium oxide, aluminum oxide, or magnesium oxide, is introduced between the passivation layer and the amorphous silicon layers to reflect unabsorbed photons back into the amorphous silicon, enhancing the creation of electron-hole pairs and improving quantum efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If photons are incident on the lower electrode or intermetallic levels, then the photons are reflected or refracted, but the quantum efficacy is reduced due to loss of unabsorbed photons
Solution Approach 1:
The patent applies this principle by converting the harmful reflection and refraction of photons at the lower electrode and intermetallic levels into a beneficial effect. Instead of allowing photons to be lost, the reflective layer captures these reflected photons and redirects them back through the amorphous silicon layers, transforming the harmful photon loss into additional opportunities for electron-hole pair generation and improving quantum efficacy
Solution Approach 2:
The patent implements this principle by nesting the reflective layer within the existing integrated circuit structure, specifically positioning it between the passivation layer and the amorphous silicon layers. This nested configuration allows the reflective layer to be integrated without significantly increasing overall device complexity while still providing the beneficial photon redirection effect
2Productivity
If a reflective layer is added to improve quantum efficacy, then unabsorbed photons are reflected back and can generate additional electron-hole pairs, but the device complexity increases
Solution Approach 1:
The reflective layer serves multiple functions within the photodiode structure: it reflects unabsorbed photons back into the amorphous silicon layers to generate additional electron-hole pairs, it can be positioned to optimize optical path length, and it integrates with the existing passivation and electrode structures. This multi-functionality justifies the addition of the layer by providing multiple benefits beyond simple photon reflection
Solution Approach 2:
The patent applies this principle by changing the optical parameters of the photodiode structure through the addition of the reflective layer. The reflective layer modifies the optical path, increasing the effective absorption length and changing the distribution of photon absorption throughout the amorphous silicon layers, thereby improving quantum efficacy without requiring fundamental redesign of the device
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 reflective layer increases the quantum efficacy of the photodiode by allowing unabsorbed photons to generate additional electron-hole pairs, thereby enhancing the performance of photosensitive integrated circuits under various illumination conditions and reducing parasitic effects from external influences.
Implementation Method 1
photons from incident electromagnetic radiation are absorbed
Implementation Method 2
An electron of the silicon then goes from the valence band to the conduction band, creating an electron-hole pair
Implementation Method 3
a reflective layer capable of reflecting photons not absorbed by the amorphous silicon layers
Data Source
AI summary
A method for producing a photosensitive integrated circuit including producing circuit control transistors, producing, above the control transistors, and between at least one upper electrode and at least one lower electrode, at least one photodiode, by amorphous silicon layers into which photons from incident electromagnetic radiation are absorbed, producing at least one passivation layer, between the lower electrode and the control transistors, and producing, between the control transistors and the external surface of the integrated circuit, a reflective layer capable of reflecting photons not absorbed by the amorphous silicon layers.