GaAs Stacked III-V Diode Drift Structure for High Reverse Voltage
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Solution Overview
Problem
Existing high-voltage semiconductor diodes face challenges in achieving high reverse voltage capabilities with low switch-on resistance and capacitance, while maintaining low series resistance and power dissipation.
Innovation Solution
A stacked III-V semiconductor diode with a GaAs structure, featuring a low n-doped and low p-doped drift region, where the n-doped drift layer is between the p-doped drift layer and the cathode, and both drift layers have specific thickness and dopant concentration ratios, along with epitaxially grown layers and metallic contact layers to minimize series resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-voltage resistant semiconductor diode with p+-n-n+ structure is used, then reverse voltage capability is improved, but switch-on resistance and capacitance increase
Solution Approach 1:
The drift region is segmented into multiple layers with different doping concentrations (first drift layer with 10^16 to 10^17 cm^-3, second drift layer with 10^15 to 10^16 cm^-3, third drift layer with 10^14 to 10^15 cm^-3). This segmentation allows the diode to achieve high reverse voltage capability while maintaining low switch-on resistance and capacitance by distributing the voltage blocking function across multiple layers with optimized doping profiles.
Solution Approach 2:
Different regions of the drift region are assigned different doping concentrations to optimize local properties. The first drift layer near the cathode has higher doping for lower series resistance, while the third drift layer near the anode has lower doping for higher breakdown voltage. This local quality variation resolves the contradiction between low switch-on resistance and high reverse voltage capability.
2Reliability
If drift region thickness is increased to improve dielectric strength, then reverse voltage capability is improved, but series resistance increases
Solution Approach 1:
The doping concentration parameter is changed progressively across the drift region layers. The first drift layer has doping of 10^16 to 10^17 cm^-3, the second has 10^15 to 10^16 cm^-3, and the third has 10^14 to 10^15 cm^-3. This parameter change allows the total drift region thickness to be increased for higher dielectric strength while the higher doping in the first layer keeps series resistance low.
3Reliability
If doping concentration in drift region is reduced to lower capacitance, then reverse voltage capability is improved, but switch-on resistance increases
Solution Approach 1:
The drift region is segmented into three layers with progressively decreasing doping concentrations. The first drift layer maintains higher doping (10^16 to 10^17 cm^-3) to keep switch-on resistance low, while the second and third layers have lower doping (10^15 to 10^14 cm^-3) to reduce capacitance and improve reverse voltage capability. This segmentation resolves the contradiction between low capacitance and low switch-on resistance.
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
Enables diodes with reverse voltages over 1100 V and low capacitance per area, improved dielectric strength, and reduced recovery charge, enhancing switch-off behavior and dielectric strength.
Implementation Method 1
The semiconductor layers can be produced by epitaxy. Preferably, epitaxy is performed by means of MOVPE and/or LPE.
Implementation Method 2
The doping of the respective GaAs semiconductor layers can be introduced during epitaxy.
Implementation Method 3
The connection contact layers are formed, for example, completely or partially of a metal, e.g., gold, or of a metal alloy and are generated, for example, by electron beam evaporation or by sputtering.
Implementation Method 4
The connection contact layers are formed, for example, completely or partially of a metal, e.g., gold, or of a metal alloy and are generated, for example, by electron beam evaporation or by sputtering.
Implementation Method 5
The p-n junction thus forms within the drift region and in an area with very low dopant concentrations.
Data Source
AI summary
A stacked III-V semiconductor diode comprising or consisting of GaAs with a highly n-doped cathode layer, a highly p-doped anode layer and a drift region arranged between the cathode layer and the anode layer, wherein the drift region has a low n-doped drift layer and a low p-doped drift layer, the n-doped drift layer is arranged between the p-doped drift layer and the cathode layer, both drift layers each have a layer thickness of at least 5 μm and, along the respective layer thickness, have a dopant concentration maximum of not more than 8·1015 cm−3, the dopant concentration maxima of the two drift layers have a ratio of 0.1 to 10 to each other and a ratio of the layer thickness of the n-doped drift layer to the layer thickness of the p-doped drift layer is between 0.5 and 3.