Radiation Detector Semiconductor Layer Bandgap Doping

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Solution Overview

Problem

Existing radiation detectors, particularly infrared detectors, face sensitivity limitations due to dark current issues, which are exacerbated by the need for cryogenic cooling, leading to energy consumption, bulkiness, and slow initialization times.

Innovation Solution

A radiation detector design featuring a stack of layers with specific semiconductor materials and doping configurations to minimize dark current, including an absorbent layer, a screen charges layer, a transition layer, and window layers with defined bandgap values and dopant densities, forming type II interfaces to reduce energy barriers and enhance sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If cryogenic cooling is used to reduce dark current, then sensitivity is improved, but energy consumption increases and device becomes bulky

Engineering Contradiction:

ImprovesensitivityVSAvoidenergy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent changes the material parameters by selecting semiconductor materials with specific bandgap values (second bandgap > first bandgap) and controlling doping densities (density in window layer > density in transition layer). This allows the detector to achieve low dark current at higher temperatures without cryogenic cooling, resolving the contradiction between sensitivity and energy consumption

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a composite structure with multiple semiconductor layers having different bandgap values and doping characteristics. The absorbent layer, transition layer, and window layer form a composite material system that optimizes both sensitivity and thermal performance, eliminating the need for cryogenic cooling

Inventive Principle:

Principle #40Composite materials

2Measurement precision

If cryogenic cooling is used to reduce dark current, then sensitivity is improved, but device size increases

Engineering Contradiction:

ImprovesensitivityVSAvoiddevice size

Core Design Contradiction:

Measurement precisionVSWeight of stationary object

Solution Approach 1:

By changing the material parameters (bandgap values and doping densities), the patent enables the detector to operate at higher temperatures without cryogenic systems, thereby reducing device size and weight while maintaining sensitivity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The composite semiconductor structure with optimized bandgap values and doping densities replaces the need for bulky cryogenic cooling systems, achieving compact device design with high sensitivity

Inventive Principle:

Principle #40Composite materials

3Measurement precision

If cryogenic cooling is used to reduce dark current, then sensitivity is improved, but initialization time increases

Engineering Contradiction:

ImprovesensitivityVSAvoidinitialization time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent changes the operating temperature parameter by designing a structure that achieves low dark current at higher temperatures, eliminating the time required for cryogenic cooling initialization while maintaining sensitivity

Inventive Principle:

Principle #35Parameter changes

4Measurement precision

If doping density is increased to reduce dark current, then sensitivity is improved, but dark current increases due to generation-recombination

Engineering Contradiction:

ImprovesensitivityVSAvoiddark current

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by having different doping densities in different layers: the window layer has higher doping density to suppress generation-recombination current, while the transition layer has lower doping density to minimize diffusion current. This localized optimization resolves the contradiction between sensitivity and dark current

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent carefully controls the doping density parameter in each layer to optimize the balance between sensitivity and dark current suppression, achieving low dark current without compromising sensitivity

Inventive Principle:

Principle #35Parameter changes

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 detector achieves improved sensitivity at temperatures greater than 80 K without the need for cryogenic cooling, reducing energy consumption and initialization time while minimizing dark current, thus enhancing operational efficiency.

Implementation Method 1

an absorbent layer configured to absorb the radiation and made from a first semiconductor material having a first bandgap value

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS10749064B2Radiation detector and associated imager

Publication Date: 2020.08.18 THALES SA

AI summary

The invention relates to a radiation detector comprising a stack of superimposed layers successively comprising: an absorbent layer configured to absorb the radiation and made from a first semiconductor material, a screen charges layer made from a semiconductor material having a second bandgap value, a transition layer made from a semiconductor material having a third bandgap value, and a transition layer made from a semiconductor material having a third bandgap value, the absorbent layer and the screen charges layer having a doping of a first type, the first window layer having a doping of a second type, a dopant density of the window layer being greater than the dopant density of the transition layer.