Semiconductor Heterojunction Neutron Detector Design
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Solution Overview
Problem
Current neutron detectors used for security and industrial applications are bulky, sensitive to radiation damage, and face challenges with the shortage of He-3 isotope, requiring additional neutron activation layers, which increases complexity and cost, and are not portable enough for effective use at seaports, airports, and border crossings.
Innovation Solution
A particle detector design featuring a semiconductor heterojunction with polycrystalline n-type and p-type layers, a thin-film structure with a back electrode having removed portions for enhanced charge collection, and a neutron activation layer with diffusion barriers to prevent material degradation, allowing for compact, durable, and low-power detection of neutrons with reduced gamma sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If He-3 gas is used in proportional counters for neutron detection, then detection sensitivity is improved, but device complexity and cost increase due to isotope shortage and need for separate activation layers
Solution Approach 1:
The patent combines the neutron activation function and charge detection function into a single integrated semiconductor device. The cadmium telluride semiconductor layer serves both as the detection medium and as the charge collection medium, eliminating the need for separate activation layers and gas fillings required in conventional proportional counters.
Solution Approach 2:
The patent extracts the He-3 gas filling and separate activation layer components from the detector structure, replacing them with a solid-state semiconductor material that performs both functions simultaneously, thereby simplifying the overall device architecture.
2Measurement precision
If semiconductor thickness is increased to 1-10 mm for effective particle detection, then detection capability is improved, but device size and portability deteriorate
Solution Approach 1:
The patent changes the material parameter from conventional semiconductors requiring 1-10 mm thickness to cadmium telluride semiconductor with high neutron absorption cross-section, enabling effective detection with thickness reduced to 10-100 micrometers. This parameter change in material selection allows thin-film construction while maintaining detection effectiveness.
3Measurement precision
If high purity single crystal semiconductor is used for particle detection, then charge collection efficiency is improved, but manufacturing cost and device complexity increase
Solution Approach 1:
The patent applies local quality by requiring high crystallinity only in the immediate vicinity of the grain boundaries and interfaces where charge collection occurs, rather than requiring perfect single-crystal quality throughout the entire thick semiconductor volume. This allows use of thinner, more easily manufactured polycrystalline or microcrystalline cadmium telluride layers.
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 solution results in a highly sensitive, compact, and durable neutron detector with low power consumption, capable of detecting neutrons effectively while minimizing gamma interference, suitable for portable and scalable applications in security and industrial settings.
Implementation Method 1
the high-energy charged particles produced by the neutron activator material will directly generate a large number of electron-hole pairs in the semiconductor as the charged particle passes through the semiconductor
Implementation Method 2
by applying a strong external voltage to create an electric field in the semiconductor which separates the electrons and holes and sweeps them to the positive and negative electrodes
Implementation Method 3
These isotopes not only capture slow or thermal neutrons, but then emit high energy charged particles that are easier to detect
Implementation Method 4
a material that has a high concentration of an isotope with a large thermal neutron absorption cross-section
Data Source
AI summary
A particle detector includes a support member. A front electrode layer is disposed over the support member. A semiconductor heterojunction is disposed over the front electrode layer. The semiconductor heterojunction has at least a polycrystalline n-type layer and at least a polycrystalline p-type layer. A back electrode layer is disposed over the semiconductor heterojunction. The back electrode includes at least one removed portion that separates a first portion of the back electrode layer from a second portion of the back electrode layer. The particle detector also includes a first body of electrically insulating material which separates a first portion of the semiconductor heterojunction from a second portion of the semiconductor heterojunction. The first body of electrically insulating material also separates a first portion of the front electrode layer from a second portion of the front electrode layer.