Diamond MISFET with δ-doped drift layer for low resistance
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Solution Overview
Problem
Semiconductor devices using diamond semiconductors face challenges with high resistance and reduced blocking voltage due to deep impurity levels, leading to increased conduction loss and maximum electric field intensity.
Innovation Solution
A semiconductor device with a δ dope structure in the drift layer, where high and low impurity density layers are alternately repeated, allowing current to flow vertically across the layers, reducing the total impurity density and maximum electric field intensity, thereby minimizing resistance and securing breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If impurity density is increased to reduce resistance, then resistance is reduced, but maximum electric field intensity becomes larger and blocking voltage becomes smaller
Solution Approach 1:
The drift layer is segmented into multiple thin layers with alternating high and low impurity densities (δ-doped layers). This segmentation allows the structure to achieve low resistance through hopping conduction in high-density regions while maintaining low maximum electric field intensity in low-density regions, thereby preserving blocking voltage.
Solution Approach 2:
Different regions of the drift layer are assigned different impurity densities to fulfill different functions: high impurity density regions provide hopping conduction paths for low resistance, while low impurity density regions maintain low maximum electric field intensity for high blocking voltage. This local differentiation resolves the contradiction between resistance and blocking voltage.
2Strength
If impurity density is reduced to increase blocking voltage, then blocking voltage is increased, but maximum electric field intensity is reduced and resistance becomes larger
Solution Approach 1:
The drift layer is divided into alternating high and low impurity density layers. The high-density segments provide hopping conduction pathways that enable low resistance even when the overall average impurity density is kept low, thus allowing high blocking voltage to be maintained.
Solution Approach 2:
The impurity density parameter is varied spatially within the drift layer, creating alternating high and low density regions. This parameter change enables the structure to achieve low resistance through hopping conduction in high-density regions while maintaining low maximum electric field intensity in low-density regions, resolving the contradiction between resistance and blocking voltage.
3Reliability
If total impurity amount is increased to reduce resistance, then resistance is reduced, but maximum electric field intensity increases and breakdown voltage is compromised
Solution Approach 1:
The total impurity amount is segmented into discrete δ-doped layers distributed throughout the drift layer. This segmentation allows hopping conduction to occur through these localized high-density regions without requiring high overall impurity content, thus maintaining low resistance while preserving breakdown voltage.
Solution Approach 2:
High impurity concentration is localized to thin δ-doped layers rather than being distributed uniformly. This local quality differentiation enables hopping conduction in the doped regions for low resistance while keeping the maximum electric field intensity low in the undoped regions, thereby maintaining breakdown voltage.
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 δ dope structure effectively reduces resistance and maximum electric field intensity while maintaining a secure breakdown voltage, without the need for increased impurity amounts, by enhancing carrier density and ionization energy in diamond semiconductor devices.
Implementation Method 1
a first layer with the first conductive type and a first density for providing a hopping conduction
Data Source
AI summary
A semiconductor device includes a MISFET having: a diamond substrate; a drift layer having a first layer with a first density for providing a hopping conduction and a second layer with a second density lower than the first density, and having a δ dope structure; a body layer on the drift layer; a source region in an upper portion of the body layer; a gate insulation film on a surface of the body layer; a gate electrode on a surface of the gate insulation film; a first electrode electrically connected to the source region and a channel region; and a second electrode electrically connected to the diamond substrate. The MISFET flows current in the drift layer in a vertical direction, and the current flows between the first electrode and the second electrode.