Vertical Diode With Series Transistors For Low Forward Voltage
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Solution Overview
Problem
Existing diodes face performance issues with high forward voltage drop and high leakage current in the reverse direction, which limits their efficiency in applications like diode rectifiers and DC/DC power converters.
Innovation Solution
The diode structure is modified by incorporating a series-connected pair of transistors with doped gates and channel-forming regions, along with a doped probe area that acts as a potential probe, to reduce the forward voltage drop while maintaining low leakage current, achieved through optimized doping levels and thin gate insulators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional diode structure is used, then the device is simple and easy to manufacture, but the forward voltage drop is high and leakage current is high
Solution Approach 1:
The diode is segmented into multiple functional regions including a first conductivity type substrate, a second conductivity type well, doped areas, and gate structures. This segmentation allows each region to be optimized independently for its specific function, reducing overall forward voltage drop while managing leakage current through controlled potential distribution.
Solution Approach 2:
Different regions of the diode are doped with different conductivity types and doping concentrations. The substrate has a first conductivity type, the well has a second conductivity type, and specific areas are heavily doped to create localized potential wells and barriers. This local quality variation optimizes carrier transport and reduces forward voltage drop in specific regions.
2Loss of energy
If thin gate insulators are used to reduce forward voltage drop, then the diode conducts at low forward voltages, but the reverse voltage might damage the insulator
Solution Approach 1:
A control structure with a potential probe is implemented to monitor and control the potential at the gate insulator before reverse voltage is applied. By beforehand establishing appropriate potential distribution through the doped areas and control gates, the insulator is protected from excessive electric fields that would cause breakdown, while still allowing thin insulator design for low forward voltage operation.
Solution Approach 2:
The potential probe in the control structure provides feedback information about the electrical conditions at the gate insulator. This feedback mechanism allows dynamic adjustment of gate potentials to prevent insulator damage during reverse bias while maintaining optimal conduction during forward bias, effectively managing the trade-off between thin insulator benefits and reliability.
3Productivity
If the diode structure is modified with transistors and control structures, then forward voltage drop is reduced, but the device complexity increases
Solution Approach 1:
The control structure is merged with the main diode structure by integrating the potential probe, control gates, and doped areas directly into the diode's substrate and well regions. This merging allows the control functionality to be achieved without adding separate discrete components, reducing overall device complexity while maintaining the ability to reduce forward voltage drop through active potential management.
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 modified diode achieves a significant reduction in forward voltage drop while maintaining comparable leakage current levels, enhancing its performance in rectifying bridges and DC-DC power converters.
Implementation Method 1
a first vertical transistor and a second transistor formed in the first portion and series-connected between the electrodes, the gate of the first transistor being doped with the first conductivity type and coupled to the upper electrode
Implementation Method 2
achieved through optimized doping levels and thin gate insulators
Data Source
AI summary
A diode includes upper and lower electrodes and first and second N-type doped semiconductor substrate portions connected to the lower electrode. A first vertical transistor and a second transistor are formed in the first portion and series-connected between the electrodes. The gate of the first transistor is N-type doped and coupled to the upper electrode. The second transistor has a P channel and has a P-type doped gate. First and second doped areas of the second conductivity type are located in the second portion and are separated by a substrate portion topped with another N-type doped gate. The first doped area is coupled to the gate of the second transistor. The second doped area and the other gate are coupled to the upper electrode.