CIGS Photodiode Hole Blocking Layer Oxygen Concentration
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Solution Overview
Problem
CIGS photodiodes with Ga2O3 layers suffer from non-optimal quantum efficiencies and high dark currents, leading to inadequate signal-to-noise ratios due to susceptibility to high leakage currents.
Innovation Solution
The photodiode structure includes a CIGS absorber layer, a Ga2O3 semiconductor layer doped with Sn, and a Ga2O3 hole blocker with an excess oxygen concentration, formed using reactive sputtering to increase resistance and dopant concentration, optimizing the depletion region and reducing dark current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If CIGS photodiodes with Ga2O3 layers are used, then environmental friendliness and visible light transmittance are improved, but dark current levels increase and quantum efficiency deteriorates
Solution Approach 1:
The photodiode structure is segmented into multiple functional layers: CIGS absorber layer, Ga2O3 semiconductor layer, and Ga2O3 hole blocking layer. Each layer is optimized independently to address specific issues - the hole blocking layer specifically targets dark current reduction while the semiconductor layer optimizes quantum efficiency, allowing the Ga2O3 material to maintain its environmental benefits without suffering from high dark current
Solution Approach 2:
The patent modifies the oxygen concentration parameter in the Ga2O3 hole blocking layer, creating an excess oxygen concentration that fundamentally changes the electrical properties of the layer. This parameter change increases the width of the depletion region and reduces carrier concentration, thereby reducing dark current while maintaining the environmental friendliness of the Ga2O3 material
2Illumination intensity
If CIGS photodiodes with Ga2O3 layers are used, then visible light transmittance is improved, but quantum efficiency deteriorates
Solution Approach 1:
Different layers are assigned different local qualities optimized for their specific functions: the CIGS absorber layer is optimized for light absorption, the Ga2O3 semiconductor layer for charge separation with high visible light transmittance, and the Ga2O3 hole blocking layer with excess oxygen for reducing dark current. This local optimization allows each layer to excel at its specific task without compromising overall device performance
Solution Approach 2:
The patent addresses quantum efficiency by extending the depletion region into the absorber layer through the excess oxygen concentration in the hole blocking layer. This dimensional extension of the depletion region into the absorber allows for better charge separation across the interface, improving quantum efficiency while maintaining the optical benefits of the Ga2O3 layers
3Reliability
If excess oxygen concentration is introduced in Ga2O3 hole blocking layer, then dark current is reduced, but manufacturing complexity increases
Solution Approach 1:
The excess oxygen concentration is incorporated into the Ga2O3 hole blocking layer during the sputtering deposition process itself, rather than requiring subsequent separate oxygenation steps. This preliminary action of incorporating excess oxygen during fabrication simplifies the overall manufacturing process while achieving the desired dark current reduction
Solution Approach 2:
The patent controls the oxygen concentration parameter during the sputtering process to create excess oxygen in the Ga2O3 hole blocking layer. By adjusting sputtering parameters (such as oxygen partial pressure, power, and deposition rate), the excess oxygen is incorporated directly during manufacturing, achieving dark current reduction without adding significant manufacturing complexity
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 configuration enhances quantum efficiency by deepening the depletion region and reduces dark current by increasing the resistance of the hole blocker, achieving a better signal-to-dark current ratio.
Implementation Method 1
disposing a hole blocking layer over the semiconductor layer, wherein the hole blocking layer is formed with a reactive sputtering process with a processing gas that comprises oxygen
Data Source
AI summary
Embodiments disclosed herein include photodiodes and methods of forming such photodiodes. In an embodiment, a method of creating a photodiode, comprises disposing an absorber layer over a first contact, wherein the absorber layer comprises a first conductivity type, and disposing a semiconductor layer over the absorber, wherein the semiconductor layer has a second conductivity type that is opposite from the first conductivity type. In an embodiment, the method further comprises disposing a hole blocking layer over the semiconductor layer, wherein the hole blocking layer is formed with a reactive sputtering process with a processing gas that comprises oxygen, and disposing a second contact over the hole blocking layer.