Ga2O3 Neutron Transmutation Doping With Thermal Neutron Annealing
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Solution Overview
Problem
Current methods for doping gallium oxide (Ga2O3) semiconductors using neutron transmutation result in highly resistive crystals due to strong compensation by neutron-induced defects, making it difficult to produce electrically conductive Ga2O3 substrates.
Innovation Solution
Subjecting Ga2O3 semiconductor materials to neutron irradiation with a higher thermal neutron content than fast neutrons, followed by annealing at temperatures of at least 700°C in a nitrogen atmosphere to produce Ge-doped Ga2O3 substrates with controlled electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If neutron transmutation doping is used to dope Ga2O3, then uniform doping is achieved, but the crystal becomes highly resistive due to strong compensation by neutron-induced defects
Solution Approach 1:
The patent changes the neutron energy parameter by using predominantly thermal neutrons (with a thermal-to-fast neutron ratio of at least 1:1, preferably at least 10:1) instead of conventional fast neutrons. This parameter change in the irradiation conditions modifies the transmutation process to produce Ge donors with reduced compensation by neutron-induced defects, thereby achieving both uniform doping and acceptable electrical conductivity
Solution Approach 2:
The patent creates a composite doping approach by combining thermal neutron transmutation (which provides uniform Ge donor distribution) with post-irradiation thermal annealing treatment. This composite process combines the advantages of uniform doping from NTD with the defect-reduction benefits of thermal annealing, resulting in material that achieves both uniformity and conductivity
2Quantity of substance
If conventional NTD with fast neutrons is used, then doping occurs, but displacement damage and defect generation increase
Solution Approach 1:
The patent changes the neutron energy parameter by using predominantly thermal neutrons (with a thermal-to-fast neutron ratio of at least 1:1, preferably at least 10:1) instead of conventional fast neutrons. Thermal neutrons have lower kinetic energy and cause significantly less atomic displacement damage while still achieving the desired transmutation and doping effect
3Manufacturing precision
If Ge doping is attempted via NTD, then doping is achieved, but Zn acceptors from Ga decay strongly compensate the Ge donors, resulting in highly resistive crystal
Solution Approach 1:
The patent changes the neutron energy parameter to use predominantly thermal neutrons, which modifies the transmutation pathway and reduces the production of Zn acceptors from Ga decay compared to fast neutron irradiation. This parameter change helps achieve a more favorable donor-to-acceptor ratio
Solution Approach 2:
The patent introduces thermal annealing treatment as an intermediary process between neutron irradiation and final material characterization. This intermediate thermal treatment step facilitates defect annealing and modifies the electrical properties of the material, helping to reduce the compensating effect of Zn acceptors and improve overall conductivity
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 approach effectively generates electrically conductive n-type Ga2O3 substrates with resistivity in the range of 0.05 to 10 Ohm·cm, reducing defect generation and enabling large-area, uniformly doped substrates suitable for high-voltage power applications without introducing residual radioactive materials.
Implementation Method 1
subjecting a Ga2O3 semiconductor material to neutron irradiation comprising a higher thermal neutron content than fast neutron content, thereby producing a Ge-doped Ga2O3 semiconductor material
Implementation Method 2
annealing the Ge-doped Ga2O3 semiconductor material at a temperature of at least 700° C. in an atmosphere of nitrogen gas, thereby generating an electrically conductive n-type Ge-doped Ga2O3 semiconductor material
Data Source
AI summary
A germanium (Ge)-doped gallium oxide (Ga2O3) semiconductor material and method of making are provided. In embodiments, a method of making the Ge-doped Ga2O3 semiconductor material includes: subjecting a Ga2O3 semiconductor material to neutron irradiation comprising a higher thermal neutron content than fast neutron content, thereby producing a Ge-doped Ga2O3 semiconductor material; and annealing the Ge-doped Ga2O3 semiconductor material at a temperature of at least 700° C. in an atmosphere of nitrogen gas, thereby generating an electrically conductive n-type Ge-doped Ga2O3 semiconductor material.