Semi-Vertical GaN Schottky Diode Current Crowding
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Solution Overview
Problem
Horizontal semiconductor devices, such as gallium nitride Schottky diodes, suffer from a current crowding effect, leading to decreased current density due to the easy impact of electric current distribution, necessitating an improvement in current density for smaller and more complex circuit designs while reducing processing costs.
Innovation Solution
A semi-vertical semiconductor device structure is implemented by disposing a first gallium nitride layer with a higher dopant concentration on a semiconductor substrate and a second gallium nitride layer, with the cathode electrode's bottom surface positioned lower than the anode electrode's, allowing electric currents to flow vertically and reducing current crowding effects, and utilizing gallium nitride for lower die costs compared to silicon carbide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If horizontal semiconductor device structure is used, then die cost is reduced, but current density decreases due to current crowding effect
Solution Approach 1:
The patent transitions from a horizontal current flow structure to a vertical current flow structure by positioning the cathode electrode lower than the anode electrode. This dimensional change in current path orientation eliminates the current crowding effect that plagues horizontal structures, thereby improving current density while maintaining manufacturing cost benefits.
Solution Approach 2:
The patent employs asymmetric electrode positioning where the cathode electrode's bottom surface is positioned lower than the anode electrode's bottom surface. This asymmetric configuration creates a vertical current flow path that prevents current crowding at the cathode-anode interface, resolving the contradiction between cost-effective horizontal structures and high-performance current density.
2Device complexity
If horizontal structure is used, then manufacturing is simpler, but current distribution is affected causing decreased current density
Solution Approach 1:
The invention introduces a vertical dimension to the current flow path by positioning electrodes at different heights. This simple structural modification changes the current distribution pattern from horizontal (prone to crowding) to vertical (uniform distribution), improving current density without significantly increasing device complexity.
Solution Approach 2:
Instead of having the cathode electrode positioned above or at the same level as the anode electrode (conventional horizontal arrangement), the patent inverts the arrangement by positioning the cathode electrode lower. This inversion creates a vertical current flow that naturally prevents current crowding, achieving high current density with minimal structural complexity.
Data Source
AI summary
A semiconductor device includes a first gallium nitride layer disposed on a semiconductor substrate, wherein the first gallium nitride layer has a first conductivity type. The semiconductor device also includes a second gallium nitride layer disposed on the first gallium nitride layer, wherein the second gallium nitride layer has the first conductivity type, and the first gallium nitride layer has a dopant concentration which is greater than that of the second gallium nitride layer. The semiconductor device further includes an anode electrode disposed on the second gallium nitride layer, a cathode electrode disposed on and in direct contact with the first gallium nitride layer, and an insulating region disposed on and in direct contact with the first gallium nitride layer, wherein the insulating region is located between the cathode electrode and the second gallium nitride layer.