Ga2O3 Schottky Diode Layer Structure for High Breakdown Voltage
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Solution Overview
Problem
The trade-off relationship between forward voltage and reverse withstand voltage in Schottky barrier diodes necessitates a solution that controls the increase in forward voltage and contact resistance while enhancing reverse breakdown voltage.
Innovation Solution
A Schottky barrier diode utilizing a Ga2O3-based semiconductor with a layered n-type structure, comprising an n− semiconductor layer with low electron carrier concentration and an n+ semiconductor layer with high electron carrier concentration, where the n− layer's thickness exceeds the depletion layer width, ensuring the reverse withstand voltage is maintained without increasing forward voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carrier concentration is lowered to increase reverse withstand voltage, then reverse withstand voltage is improved, but forward voltage increases due to increased electric resistance
Solution Approach 1:
The semiconductor layer is divided into multiple regions with different carrier concentrations: a first semiconductor layer with lower carrier concentration (1×10^16 to 1×10^18 cm^-3) adjacent to the Schottky electrode for high reverse withstand voltage, and a second semiconductor layer with higher carrier concentration (1×10^18 to 1×10^20 cm^-3) for low electric resistance. This segmentation allows each region to optimize for its specific function, resolving the contradiction between reverse withstand voltage and forward voltage.
Solution Approach 2:
Different regions of the semiconductor layer are assigned different local properties (carrier concentrations) to fulfill different functional requirements. The first semiconductor layer has low carrier concentration locally to achieve high reverse withstand voltage near the Schottky electrode, while the second semiconductor layer has high carrier concentration locally to reduce overall electric resistance and forward voltage.
2Reliability
If carrier concentration is lowered to increase reverse withstand voltage, then reverse withstand voltage is improved, but contact resistance with ohmic electrode layer increases
Solution Approach 1:
The semiconductor structure is segmented into a first semiconductor layer with low carrier concentration for high reverse withstand voltage and a second semiconductor layer with high carrier concentration for low contact resistance with the ohmic electrode. This segmentation resolves the contradiction by assigning different carrier concentrations to different functional zones.
Solution Approach 2:
The second semiconductor layer has high carrier concentration (1×10^18 to 1×10^20 cm^-3) specifically at the region where the ohmic electrode contacts, ensuring low contact resistance. Meanwhile, the first semiconductor layer maintains low carrier concentration for high reverse withstand voltage, resolving the local quality conflict.
3Reliability
If Ga2O3-based semiconductor is used to achieve high reverse withstand voltage, then reverse withstand voltage is improved, but forward voltage increases due to material properties
Solution Approach 1:
The carrier concentration parameter is changed across different regions of the Ga2O3-based semiconductor layer. By creating a gradient from low carrier concentration (1×10^16 to 1×10^18 cm^-3) near the Schottky electrode to high carrier concentration (1×10^18 to 1×10^20 cm^-3) near the ohmic electrode, the patent optimizes both reverse withstand voltage and forward voltage characteristics of the Ga2O3 material.
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 effectively reduces forward voltage drop and contact resistance while achieving reverse withstand voltages of up to 10000 V by leveraging Ga2O3's high electric field-breakdown strength and controlled electron carrier concentrations.
Implementation Method 1
a first semiconductor layer in Schottky-contact with the electrode layer and a second semiconductor layer having an electron carrier concentration higher than the first semiconductor layer are formed in the n-type semiconductor layer
Implementation Method 2
a metal and a semiconductor are Schottky-contacted with each other
Implementation Method 3
a thickness of the first semiconductor layer is greater than a thickness of a depletion layer corresponding to a reverse withstand voltage
Data Source
AI summary
A Schottky barrier diode, including a first n-type semiconductor layer including a β-Ga2O3-based single crystal epitaxial layer and having a first carrier concentration that determines reverse breakdown voltage and forward voltage, a second n-type semiconductor layer including a β-Ga2O3-based single crystal substrate and having a second carrier concentration that is higher than the first carrier concentration and determines forward voltage, a Schottky electrode provided on a surface of the first n-type semiconductor layer on the opposite side to the second n-type semiconductor layer, and an ohmic electrode provided on a surface of the second n-type semiconductor layer on the opposite side to the first n-type semiconductor layer. The β-Ga2O3-based single crystal substrate includes a surface that has a plane orientation rotated by an angle of not more than 37.5° from a (010) plane.