Diamond Schottky Diode JBS Field Shielding
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Solution Overview
Problem
The challenge in manufacturing diamond-based unipolar power diodes is to limit the electric field at the boundary between the diamond substrate and the Schottky metal, as current methods like selective doping are not applicable to diamond, leading to increased reverse current and potential thermal destruction due to high reverse voltage.
Innovation Solution
The introduction of n-doped JBS areas created by epitaxial layer growth and structured using photolithographic techniques, which are then etched to shield the electric field from the Schottky transition, allowing adjustment of the reverse voltage by altering the distance between the JBS areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If selective doping is used to limit the electric field, then the reverse current is reduced, but this method is not applicable to diamond
Solution Approach 1:
The patent introduces an intermediate layer (first doped layer with opposite conductivity type) between the Schottky metal contact and the drift region to limit the electric field. This intermediary layer serves as a mediator that prevents the direct application of high reverse voltage to the Schottky transition, thereby reducing reverse current without requiring selective doping of the diamond substrate itself.
Solution Approach 2:
The patent applies local quality by creating a specifically doped region (first doped layer) with different conductivity type and doping concentration than the drift region. This localized modification of electrical properties at the interface between the Schottky contact and drift region enables effective electric field limitation while maintaining the overall diamond structure.
2Device complexity
If the electric field at the Schottky boundary is not limited, then the device structure is simpler, but the reverse current increases significantly leading to thermal destruction
Solution Approach 1:
The patent implements preliminary action by pre-structuring the first doped layer and second doped layer before applying the Schottky metal contact. These pre-formed doped regions create potential barriers that will limit the electric field during subsequent reverse voltage application, preventing thermal destruction before it occurs.
Solution Approach 2:
The first doped layer acts as an intermediary structure between the Schottky contact and the drift region, providing electric field limitation functionality. This intermediary layer protects the Schottky transition from direct exposure to high reverse voltage, reducing reverse current and preventing thermal destruction while maintaining device functionality.
3Power
If diamond is used for high voltage applications, then the power handling capability is improved, but the manufacturing methods for field limitation are not available
Solution Approach 1:
The patent utilizes parameter changes by varying the doping concentration and conductivity type in different layers (first doped layer with high opposite-type doping, second doped layer with lower same-type doping). These parameter modifications create the necessary electric field limitation structure in diamond, enabling high voltage applications despite the unavailability of conventional selective doping methods.
Solution Approach 2:
The patent creates a composite structure within the diamond device by combining regions of different doping types and concentrations (first doped layer, second doped layer, drift region). This composite doping structure enables field limitation functionality in diamond, making high voltage power applications feasible despite manufacturing challenges.
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
This method effectively shields the Schottky transition from the electric field, reducing reverse current and enabling the use of diamond-based unipolar power diodes in high-temperature and high-voltage applications, such as satellite communication and transmission of electricity with voltages above 10 kV.
Implementation Method 1
JBS areas of doped diamond having a second conductivity type, opposite the conductivity type of the drift region, are constructed on a side of the drift region opposite the anode. A Schottky metal is applied over the JBS regions... The JBS structure shields an electric field generated by an applied reverse voltage from the Schottky transition.
Implementation Method 2
an n-doped layer is applied to the typically p-doped drift region, e.g. by means of epitaxial layer growth
Implementation Method 3
A photolithographic mask may be applied and the n-doped layer is removed by dry or wet chemical etching
Data Source
AI summary
The invention disclosure describes a manufacturing method for realizing so-called JBS areas for a unipolar power diode on the basis of diamond. In this special method, an n-doped layer is applied to the typically p-doped drift region, e.g. by means of epitaxial layer growth. The applied n-doped layer is then removed again in defined areas. A photolithographic mask may be applied and the n-doped layer is removed by dry or wet chemical etching. Having structured the JBS areas, the Schottky metal is applied to the entire surface. The resulting JBS structure shields an electric field generated by an applied reverse voltage from the Schottky transition. The reverse voltage from which the Schottky transition is fully shielded can be adjusted by altering the distance between the JBS areas.