SiC Junction Barrier Schottky Rectifier Leakage Reduction
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Solution Overview
Problem
Conventional SiC Schottky barrier diodes experience high leakage current under reverse bias due to the image force induced barrier lowering, which affects their performance in high temperature, high frequency, and high power applications.
Innovation Solution
The SiC junction barrier controlled Schottky rectifier incorporates a heavily-doped n-type SiC substrate, a p-type doping region, and junction field-effect regions with N circular and (N-1) inter-circle regions, forming a Schottky barrier and Ohmic contact to reduce leakage current and increase the Schottky contact area, thereby enhancing the device's performance under reverse bias.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a metal with lower work function is selected to reduce Schottky barrier, then forward voltage drop is reduced, but leakage current at reverse bias increases due to image force induced barrier lowering
Solution Approach 1:
The Schottky contact area is segmented into multiple circular regions separated by p-type doping regions. This segmentation creates multiple independent Schottky barriers while the p-type regions act as isolation barriers, preventing lateral leakage current paths between adjacent circular regions.
Solution Approach 2:
p-type doping regions are introduced as intermediary elements between the n-type drift layer and the Schottky contact. These p-type regions modify the local electric field distribution and create potential barriers that suppress leakage current while allowing the Schottky barrier to maintain low forward voltage drop.
2Productivity
If Schottky contact area is increased to improve current density, then forward current capability is improved, but reverse leakage current also increases
Solution Approach 1:
The Schottky contact is divided into N circular regions with (N-1) inter-circle regions between them. This segmentation increases the total Schottky contact area for improved forward current capability while the p-type doping regions in the inter-circle areas block leakage current paths, allowing each circular region to operate independently with suppressed leakage.
Solution Approach 2:
Different regions of the contact structure are given different properties: circular regions have Schottky barriers optimized for low forward voltage drop and high current density, while the inter-circle regions have p-type doping optimized for leakage suppression. This local differentiation allows simultaneous optimization of both forward and reverse characteristics.
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 design effectively reduces leakage current and improves the forward current density by forming a uniform depletion region that shields the surface electric field, resulting in improved performance and ruggedness compared to conventional Schottky barrier diodes.
Implementation Method 1
the Schottky barrier would be further lowered due to the image force induced barrier lowering, which will result in a considerable leakage current at a reverse bias
Implementation Method 2
the junction field-effect regions are surrounded by the p-type doping region to form the N circular regions and the (N−1) inter-circle regions between every two of the circular regions
Data Source
AI summary
A SiC junction barrier controlled Schottky rectifier includes a SiC substrate, a n-type drift layer, a p-type doping region, a plurality of junction field-effect regions, a first metal layer and a second metal layer. The drift layer is disposed on the SiC substrate. The junction field-effect regions are disposed in the drift layer and are surrounded by the p-type doping region. The first metal layer is disposed on the drift layer. The second metal layer is disposed at one side of the SiC substrate away from the drift layer. Through N circular regions and (N−1) inter-circle regions each connecting two of the circular regions, as well as geometric characteristics of the circular regions and the inter-circle regions, a leakage current of devices is effectively reduced and ruggedness is increased to improve an issue of a large leakage current of a conventional Schottky barrier diode.