Radiation Detector Work Function Engineering

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Solution Overview

Problem

Existing radiation detectors, such as those with p-i-n junctions, require cooling for operation and have limitations in sensitivity and energy resolution, and the configuration with indium as the anode electrode material does not provide increased photo-peak count sensitivity.

Innovation Solution

A radiation detector design featuring a semiconductor substrate with a cathode electrode on one surface and anode electrodes on the opposite surface, where the cathode electrode material has a lower work function than the anode electrode material, and a forward bias is applied to maintain the anode at a higher potential, allowing for improved charge injection and sensitivity without the need for cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If cooling is implemented for operation, then detector sensitivity is improved, but device complexity and operational cost increase

Engineering Contradiction:

Improvedetector sensitivityVSAvoidcooling system requirement

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent changes the work function parameter of the electrode materials to achieve room temperature operation. By selecting cathode material with lower work function than anode material, the detector achieves improved sensitivity without cooling, resolving the contradiction between sensitivity improvement and device complexity reduction

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent eliminates the need for expensive and complex cooling systems by using appropriate material selection. The simpler room-temperature operating design reduces both device complexity and operational costs while maintaining detection capability

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If indium is used as anode electrode material, then charge injection is enhanced, but photo-peak count sensitivity is not increased

Engineering Contradiction:

Improvecharge injectionVSAvoidphoto-peak count sensitivity

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

Instead of using indium as the anode material as in conventional designs, the patent inverts the approach by using indium or other low work function materials as the cathode material. This reversal enables both improved charge injection and increased photo-peak count sensitivity simultaneously

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent applies different material properties to different electrodes based on their specific functions. The cathode uses low work function material optimized for charge injection, while the anode uses appropriate material for signal collection, achieving optimized performance at each interface

Inventive Principle:

Principle #3Local quality

3Measurement precision

If forward bias is applied to maintain anode at higher potential, then sensitivity is improved, but leakage current may increase

Engineering Contradiction:

Improvedetector sensitivityVSAvoidleakage current

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent changes the work function parameter relationship between electrodes to optimize the balance between sensitivity and leakage current. The specific selection of electrode materials with appropriate work function differences enables forward bias operation that improves sensitivity while controlling leakage current

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 design enhances detector sensitivity, maintains low leakage current, and achieves high energy resolution, enabling reliable room temperature operation and suitability for mass production.

Implementation Method 1

a cathode electrode located on the front surface of said semiconductor substrate configured so as to receive radiation

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

The work function of the cathode electrode material contacting the front surface of the semiconductor substrate is lower than the work function of the anode electrode material contacting the rear surface of the semiconductor substrate

Methodology Applied

Scientific EffectWork function difference:

Implementation Method 3

applying a forward bias to the detector to maintain the anode electrodes at a higher potential than the cathode electrode and such that the signal is collected from the anode electrodes

Methodology Applied

Scientific EffectElectric field: Electric Field

Data Source

PatentUS9202961B2Imaging devices with solid-state radiation detector with improved sensitivity

Publication Date: 2015.12.01 REDLEN TECH

AI summary

A radiation detector includes a semiconductor substrate having opposing front and rear surfaces, a cathode electrode located on the front surface of the semiconductor substrate configured so as to receive radiation, and a plurality of anode electrodes formed on the rear surface of said semiconductor substrate. A work function of the cathode electrode material contacting the front surface of the semiconductor substrate is lower than a work function of the anode electrode material contacting the rear surface of the semiconductor substrate.