Diode P-Type Hole Implantation Layer Voltage Ringing
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Solution Overview
Problem
Conventional fast recovery diodes experience significant voltage ringing during switching operations due to rapid depletion of carriers in the drift layer, which can be exacerbated by the introduction of a p layer intended to mitigate this issue.
Innovation Solution
A diode design incorporating a p type hole implantation layer with a diameter of 20 μm or more and a disposition rate of 20% or more, strategically positioned to enhance voltage drop and prevent carrier depletion, thereby effectively restraining voltage ringing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a p layer is disposed at a part of an n layer on the cathode side to supply carriers during recovery operation, then voltage ringing is restrained, but voltage ringing may contrarily become large if the size or disposition rate of the p layer is not properly controlled
Solution Approach 1:
The patent specifies precise parameter ranges for the p layer: disposition rate of 1% to 50% and area ratio of 0.1% to 10%. By defining these quantitative parameters, the invention transforms the qualitative control problem into a measurable and controllable manufacturing parameter, ensuring carrier supply while preventing excessive voltage ringing.
2Speed
If carriers are rapidly depleted from the drift layer during switching operation, then reverse recovery time is shortened, but voltage ringing occurs due to great change in electric current
Solution Approach 1:
The p layer is pre-positioned on the cathode side before switching operation occurs. During the recovery phase, this pre-positioned p layer immediately begins supplying carriers to the drift layer, preventing rapid carrier depletion and the associated voltage ringing before it can occur.
Solution Approach 2:
The p layer acts as an intermediary carrier source between the cathode and the drift layer. It provides a controlled supply of carriers during the recovery operation, mediating the transition and preventing direct rapid depletion that would cause voltage ringing.
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 diode effectively suppresses voltage ringing by ensuring sufficient hole implantation from the p type hole implantation layer, maintaining stable carrier levels and reducing voltage peaks during switching operations.
Implementation Method 1
a p type hole implantation layer selectively disposed at the n type cathode layer
Data Source
AI summary
A diode includes an n type semiconductor layer including an n type cathode layer and an n type drift layer that has an impurity concentration lower than the n type cathode layer and that is disposed on the n type cathode layer, a p type anode layer disposed at a surface part of the n type drift layer, a p type hole implantation layer selectively disposed at the n type cathode layer, an anode electrode electrically connected to the p type anode layer, and a cathode electrode electrically connected to the n type cathode layer and to the p type hole implantation layer, and the p type hole implantation layer has a diameter of 20 μm or more.