GaN Schottky Diode with Local N-Doping for Low Onset Voltage
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Solution Overview
Problem
Conventional Schottky barrier diodes have high onset voltage, leading to significant conduction loss and early breakdown due to metal spiking and difficulties in achieving good ohmic characteristics with GaN materials, which affects the efficiency of switching power supplies.
Innovation Solution
A Schottky barrier diode structure with selective n-type doping regions under the anode and cathode electrode layers, creating two junctions with different Schottky barriers to reduce onset voltage while maintaining breakdown voltage, achieved through silicon ion doping and careful electrode layer positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional AlGaN/GaN Schottky barrier diode structure is used, then breakdown voltage is maintained, but onset voltage is high (1V-1.5V) causing serious conduction loss
Solution Approach 1:
The patent introduces an n-type doping region locally beneath the anode electrode layer, creating a non-uniform doping structure. This local doping modifies the electric field distribution and Schottky barrier height specifically in the high-field region under the anode, reducing the onset voltage and conduction loss without compromising the overall breakdown voltage characteristics of the diode.
Solution Approach 2:
The patent changes the doping concentration parameter by introducing an n-type doping region with specific doping concentration (1×10^18 to 1×10^20 atoms/cm³) beneath the anode. This parameter modification alters the local electric field and Schottky barrier properties, enabling lower onset voltage while maintaining adequate breakdown voltage through careful control of doping concentration and depth.
2Reliability
If GaN material is used for Schottky barrier diode, then high breakdown voltage is achieved, but metal spiking occurs around ohmic contact region causing early breakdown
Solution Approach 1:
The patent extracts or removes the problematic metal ohmic contact layer from the GaN structure. By eliminating the metal-GaN ohmic contact interface, the source of metal spiking is removed entirely, preventing the formation of high electric field regions that would lead to early breakdown while maintaining the desired high breakdown voltage characteristics.
Solution Approach 2:
The patent introduces an n-type doping region as an intermediary layer between the anode electrode and the GaN drift layer. This doped region acts as a mediator that modifies the electrical characteristics at the electrode-semiconductor interface, reducing the Schottky barrier height and onset voltage without requiring a metal ohmic contact that would cause spiking issues.
3Reliability
If GaN material is used for Schottky barrier diode, then high breakdown voltage is achieved, but fabrication of ohmic resistance is difficult resulting in poor ohmic characteristics
Solution Approach 1:
The patent extracts or eliminates the complex metal ohmic contact fabrication process from the GaN device structure. By removing the requirement for metal-GaN ohmic contacts, the difficult fabrication steps associated with achieving good ohmic characteristics are eliminated, simplifying the manufacturing process while maintaining high breakdown voltage performance.
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 proposed diode design achieves a lower onset voltage without sacrificing breakdown voltage, improving efficiency and reducing conduction loss, as evident from the diagrams showing reduced onset voltage and maintained breakdown voltage performance.
Implementation Method 1
The junction formed between the metal arranged to be the anode of the Schottky barrier diode and the barrier layer of the Schottky barrier diode is the Schottky contact
Implementation Method 2
a first n-type doping region, formed in the upper layer and under the first electrode layer, and contacting the first electrode layer
Implementation Method 3
a high electric field is produced in the local regions, further resulting in the early breakdown of the GaN Schottky barrier diode
Data Source
AI summary
A Schottky barrier diode includes a substrate, a buffer layer formed on the substrate, an upper layer formed on the buffer layer, a first electrode layer formed on the upper layer as an anode of the Schottky barrier diode, a second electrode layer formed on the upper layer as a cathode of the Schottky barrier diode, and a first n-type doping region formed in the upper layer and under the first electrode layer, and contacting the first electrode layer. An edge of the first n-type doping region and an edge of the first electrode layer are separated by a first predetermined distance at a first direction at which the first electrode layer faces the second electrode layer.