Normally-Off Heterostructure Device With Iodine Ion Implantation
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Solution Overview
Problem
Current high power semiconductor devices, such as HFETs, are normally-on, which is undesirable for switching applications due to their inability to control conductivity without an applied potential, and lack a high threshold voltage and high channel charge density, making them impractical for devices like inverters or converters.
Innovation Solution
A semiconductor heterostructure device with a multi-layer structure including a third region with iodine ions implanted between the source and drain regions, allowing for a switchable electrically conductive pathway that is initially non-conductive but becomes conductive upon gate voltage application, achieving a normally-off mode with a high threshold voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heterostructure field effect transistor (HFET) is designed with a heterojunction to achieve high electron mobility and low on-state resistance, then the channel conductivity is improved, but the device becomes normally-on and loses the ability to control conductivity without applied potential
Solution Approach 1:
The patent modifies the electrical parameters of the HFET by introducing a gate electrode and adjusting the band structure through heterojunction design. The gate voltage parameter is used to control the channel conductivity, transitioning the device from normally-on to normally-off state while maintaining high electron mobility through the heterostructure interface
Solution Approach 2:
The gate electrode acts as an intermediary control element between the source and drain regions. By applying voltage to the gate, the channel conductivity is modulated without direct current flow through the gate, enabling controlled switching while preserving the low on-state resistance provided by the heterostructure channel
2Reliability
If a normally-on HFET is used to achieve high electron mobility through heterojunction, then low on-state resistance is obtained, but the device cannot function as a switching device in inverters or converters
Solution Approach 1:
The patent transforms the static normally-on HFET into a dynamic switching device by introducing gate control. The channel conductivity becomes dynamically adjustable through gate voltage application, enabling the device to switch between on and off states for use in inverters, converters, and other switching applications while maintaining low on-state resistance when conductive
3Temperature
If a heterostructure HFET is designed for high power applications, then good thermal properties and high breakdown voltage are achieved, but the device lacks high threshold voltage and high channel charge density
Solution Approach 1:
The patent employs a composite heterostructure combining different semiconductor materials with complementary properties. The heterojunction incorporates materials optimized for high breakdown voltage and thermal conductivity, while the gate structure and doping profiles are designed to achieve high threshold voltage and high channel charge density simultaneously
Solution Approach 2:
The patent applies different material compositions and doping concentrations to different regions of the device. The channel region uses materials optimized for high electron mobility and thermal conductivity, while the gate region and depletion layer use materials and profiles designed to establish high threshold voltage, creating locally optimized properties throughout the structure
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 device operates as a normally-off heterostructure field effect transistor with improved threshold voltage and channel charge density, reducing leakage currents and enhancing efficiency for high power, high temperature, and high frequency applications, suitable for devices like power diodes and converters.
Implementation Method 1
implantation of ions into a portion of a surface of a multi-layer structure. Iodine ions are implanted between a first region and a second region to form a third region
Data Source
AI summary
A method of manufacturing a heterostructure device is provided that includes implantation of ions into a portion of a surface of a multi-layer structure. Iodine ions are implanted between a first region and a second region to form a third region. A charge is depleted from the two dimensional electron gas (2DEG) channel in the third region to form a reversibly electrically non-conductive pathway from the first region to the second region. On applying a voltage potential to a gate electrode proximate to the third region allows electrical current to flow from the first region to the second region.