GaN HEMT Radiation Sensor With Impact Ionization Amplification
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Solution Overview
Problem
Current silicon-based radiation detectors in high-radiation environments, such as the Large Hadron Collider, face performance degradation and limited lifespan due to inability to withstand high radiation fluences, necessitating the development of more resilient sensor technology.
Innovation Solution
A gallium nitride (GaN) high electron mobility transistor (HEMT) device is designed with a specific layer structure including a substrate, nucleation layer, GaN buffer layer, aluminum nitride spacer layer, barrier layer, and silicon nitride passivation layer, capable of detecting ionizing radiation through charge carrier generation and multiplication via impact ionization, enhancing sensitivity and signal amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silicon-based detectors are used in high-radiation environments, then device complexity is low and manufacturing is easy, but reliability deteriorates due to performance degradation under high radiation fluence
Solution Approach 1:
The patent employs a composite material structure consisting of multiple layers including GaN buffer layer, AlN spacer layer, AlGaN barrier layer, and GaN cap layer. This composite structure leverages the superior radiation hardness of GaN materials while maintaining device functionality, directly addressing the reliability issue in high-radiation environments.
Solution Approach 2:
The invention applies different material compositions and structures to specific regions of the detector. For example, the AlN spacer layer is strategically positioned to provide localized radiation damage resistance, while the AlGaN barrier layer optimizes carrier transport in critical regions, ensuring overall device reliability without uniform complexity throughout.
2Measurement precision
If traditional GaN diode structures are used for radiation sensing, then radiation hardness is improved, but measurement precision deteriorates due to reduced sensitivity to weakly ionizing radiation
Solution Approach 1:
The patent optimizes critical parameters including the thickness of the GaN buffer layer (5-20 μm), the composition gradient of AlGaN barrier layer (Al content 20-50%), and the doping concentration in the channel layer. These parameter adjustments enhance the detection sensitivity to weakly ionizing radiation while preserving radiation hardness through the GaN-based structure.
Solution Approach 2:
The invention introduces a multi-layered heterostructure that dynamically responds to different radiation types and energies. The varying bandgaps and carrier mobilities across different layers enable adaptive detection characteristics, improving sensitivity to weakly ionizing radiation without sacrificing resistance to high radiation fluence.
3Measurement precision
If GaN HEMT structure is implemented for radiation detection, then measurement precision is improved through enhanced sensitivity, but device complexity increases due to multiple layered structure
Solution Approach 1:
The detector is segmented into functionally distinct layers: GaN buffer layer for radiation interaction, AlN spacer layer for structural stability, AlGaN barrier layer for carrier confinement, and GaN cap layer for contact formation. This segmentation allows each layer to be optimized independently for its specific function, achieving high signal-to-noise ratio while managing complexity through functional specialization.
Solution Approach 2:
The GaN HEMT structure serves multiple functions simultaneously: the GaN buffer layer acts as both radiation interaction medium and structural foundation, the AlGaN barrier layer provides both carrier confinement and electric field management, and the overall structure enables both radiation detection and signal amplification, reducing the need for additional components.
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 GaN HEMT device demonstrates improved sensitivity and signal-to-noise ratio, capable of detecting ionizing radiation with a signal-to-noise ratio of ~100, effectively addressing the limitations of silicon-based detectors in harsh radiation conditions.
Implementation Method 1
the GaN atoms are ionized, directly or indirectly, to generate charge carriers as the radiation travels through the GaN HEMT
Implementation Method 2
multiplied by impact ionization by a high electric field at the gate edge facing the drain contact
Data Source
AI summary
A semiconductor high electron mobility transistor (HEMT)-based device configured to detect ionizing radiation, wherein the device comprises: a substrate; a nucleation layer formed on the substrate; a gallium nitride (GaN) buffer layer arranged on the nucleation layer; a GaN channel layer arranged on the GaN buffer layer; an aluminum nitride (A1N) spacer layer arranged on the GaN channel layer; a barrier layer arranged on the A1N spacer layer; a GaN cap layer arranged on the barrier layer; an electrically insulating silicon nitride (SiNx) passivation layer arranged on the GaN cap layer; a source, a drain and a gate, wherein the source and the drain are formed on the GaN cap layer; wherein charge carriers generated by the radiation in the underlying GaN layers are collected in the GaN channel layer and multiplied by impact ionization by a high electric field at the gate edge facing the drain contact.