Quasi-Vertical GaN JBS Diode Structure for Monolithic Three-Phase DRU
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Solution Overview
Problem
Existing DRU rectifying systems face challenges with low integration, limited power handling capacity, and narrow voltage application range due to the use of Si-based discrete devices, which are nearing the theoretical limits of their material properties, leading to low device power density and difficulty in miniaturization.
Innovation Solution
A quasi-vertical JBS diode is developed using a Si substrate with N+ GaN conductive and N-type GaN drift layers, featuring concentrically distributed groove structures filled with Mg-doped P-type BN material, integrated into a monolithic three-phase DRU, enhancing withstand voltage and power handling capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Si-based discrete devices are used in DRU rectifying circuits, then the device structure is simple and easy to manufacture, but the integration is low and the power density is limited
Solution Approach 1:
The patent merges multiple discrete Si-based diode devices into a single integrated GaN-based DRU module, combining six diodes into one monolithic structure. This merging approach directly addresses the low integration problem by consolidating multiple functional units into a unified device while maintaining manufacturing feasibility through standardized GaN fabrication processes
Solution Approach 2:
The patent transitions from planar 2D device layout to a quasi-vertical 3D structure with multi-layer GaN epitaxial layers and vertical current flow paths. This dimensional change enables higher power density by utilizing the vertical dimension for current conduction, allowing multiple diodes to be stacked and integrated in a compact footprint
2Ease of manufacture
If Si-based materials are used for diodes, then the manufacturing process is mature, but the power density is low and miniaturization is difficult under high-power conditions
Solution Approach 1:
The patent changes the fundamental material parameter from Si to GaN, exploiting GaN's superior critical breakdown field strength (approximately 3.3 times that of Si). This parameter change enables the device to handle the same power level with reduced voltage stress, allowing for smaller device dimensions and lower operating voltages while maintaining or improving power density
Solution Approach 2:
The patent employs a composite structure consisting of multiple GaN layers with different doping types and concentrations (n-type drift layer, n+ -type contact layer, p-type barrier layer) stacked vertically. This composite material approach optimizes each layer's function for its specific role in voltage blocking, current conduction, and electric field management, achieving high power density in a compact volume
3Volume of moving object
If existing small-size DRU circuits are designed, then the device size is reduced, but the voltage application range is narrow and the withstand voltage is low
Solution Approach 1:
The patent segments the voltage blocking function across multiple GaN layers with different doping configurations, including an n-type drift layer for voltage support, an n+ -type contact layer for current conduction, and a p-type barrier layer for electric field management. This segmentation allows each layer to be optimized for its specific function, enabling the compact device to achieve high withstand voltage capability
Solution Approach 2:
The patent applies local quality optimization by creating regions with different doping concentrations and material compositions at specific locations within the device structure. The p-type barrier layer is strategically positioned at the junction region to locally enhance electric field management and voltage blocking capability, while the n+ contact layer provides localized low-resistance current paths, enabling high voltage handling in a small volume
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 quasi-vertical JBS diode improves integration, reduces circuit volume, and enhances reliability by leveraging GaN's high breakdown field strength and JBS ring structure, broadening the voltage application window and increasing power handling capacity.
Implementation Method 1
utilizes the high breakdown field strength of the BN material, the electric field regulation capability of the JBS ring structure
Implementation Method 2
the suppression effect of P-BN covering the device sidewall on sidewall leakage current
Implementation Method 3
leveraging GaN's high breakdown field strength
Data Source
AI summary
A quasi-vertical JBS diode and a monolithic integrated three-phase DRU are provided. The quasi-vertical JBS diode includes a Si substrate, a N+ GaN conductive layer and an N-type GaN drift layer sequentially disposed from bottom to top. A top region of the N-type GaN drift layer defines groove structures distributed concentrically and annularly, and a Mg-doped P-type BN material is disposed on an inside of each of the groove structures and a side of the N-type GaN drift layer. An anode is disposed on a surface of the N-type GaN drift layer defining the groove structures. A cathode is disposed on a surface of the N+ GaN conductive layer at intervals around the N-type GaN drift layer. The monolithic integrated three-phase DRU includes three AC input terminals, two rectified DC output terminals and diode groups corresponding to six rectifier bridge arms. The diodes each are the quasi-vertical JBS diode.