GaN MPS Diode Fabrication via Regrowth and Etch Back
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Solution Overview
Problem
Current power electronics devices lack efficient high-voltage switches with low capacitance and very low leakage current, particularly in reverse bias conditions, limiting their performance in high-voltage applications.
Innovation Solution
The development of merged P-i-N Schottky (MPS) diodes using gallium-nitride (GaN) based epitaxial layers, fabricated through a blanket regrowth and etch back process, which combines the low turn-on voltage of Schottky diodes with the low reverse leakage current of P-i-N diodes, utilizing p-type regions within the Schottky contact and appropriately spaced p-n junctions for edge termination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If standard Schottky diode structure is used, then low turn-on voltage is achieved, but high reverse leakage current occurs
Solution Approach 1:
The patent merges the Schottky diode structure with P-i-N diode characteristics by forming p-type regions within the Schottky contact area and creating appropriately spaced p-n junctions. This hybrid structure combines the low turn-on voltage advantage of Schottky diodes with the low reverse leakage current advantage of P-i-N diodes, resolving the contradiction between these two opposing characteristics.
Solution Approach 2:
The patent applies local quality by creating p-type regions specifically within the Schottky contact area and forming p-n junctions at specific locations for edge termination. This localized modification of the Schottky diode structure allows different regions to perform different functions: the Schottky contact provides low turn-on voltage while the embedded p-n junctions suppress reverse leakage current.
2Reliability
If higher blocking voltage is achieved, then high-voltage switching capability is improved, but forward resistance increases
Solution Approach 1:
The patent utilizes GaN material parameters including high critical electric field and high electron mobility to achieve high blocking voltage without proportionally increasing forward resistance. The material parameter changes enable the device to maintain excellent trade-offs between blocking voltage and forward resistance, resolving the contradiction between these two opposing performance parameters.
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 MPS diodes exhibit superior performance with lower leakage currents and faster switching speeds compared to standard Schottky diodes, offering a high voltage switch with excellent trade-offs between blocking voltage and forward resistance, suitable for high-voltage applications due to GaN's material properties.
Implementation Method 1
forming an n-type GaN-based epitaxial layer coupled to the first surface of the n-type GaN-based substrate
Implementation Method 2
removing a portion of the n-type GaN-based epitaxial layer to form a plurality of protrusions
Data Source
AI summary
An MPS diode includes a III-nitride substrate characterized by a first conductivity type and a first dopant concentration and having a first side and a second side. The MPS diode also includes a III-nitride epitaxial structure comprising a first III-nitride epitaxial layer coupled to the first side of the substrate, wherein a region of the first III-nitride epitaxial layer comprises an array of protrusions. The III-nitride epitaxial structure also includes a plurality of III-nitride regions of a second conductivity type, each partially disposed between adjacent protrusions. Each of the plurality of III-nitride regions of the second conductivity type comprises a first section laterally positioned between adjacent protrusions and a second section extending in a direction normal to the first side of the substrate. The MPS diode further includes a first metallic structure electrically coupled to one or more of the protrusions and to one or more of the second sections.