GaN Schottky Diode Structure With 2DEG Depletion for Low Capacitance
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Solution Overview
Problem
Conventional finger-shaped Schottky diodes used in high-frequency radio wave rectenna systems have high on-resistance due to the access region, which limits efficiency and operation speed, and cannot utilize high voltage-resistant structures without increasing parasitic capacitance.
Innovation Solution
A diode structure comprising an undoped GaN layer, an AlxGa1-xN layer, a Mg-doped p-type InyGa1-yN layer with an island-like shape, and metal and cathode electrodes, where a two-dimensional electron gas is depleted under the p-type InyGa1-yN layer at zero bias, reducing capacitance and allowing for low forward turn-on voltage, thereby enhancing efficiency and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a finger-shaped access layer is used in conventional GaN-based Schottky diodes, then the diode structure can be fabricated, but the on-resistance increases due to the resistance of the access layer
Solution Approach 1:
The invention extracts and removes the problematic access layer from the diode structure. By depleting the two-dimensional electron gas in the AlGaN layer through the p-type InGaN layer, the access layer is effectively taken out of the conduction path, eliminating its harmful resistance effect while preserving the rectifying function through the Schottky contact at the anode electrode.
Solution Approach 2:
The invention changes the electrical parameters of the AlGaN layer by inducing complete depletion of two-dimensional electron gas through the p-type InGaN layer. This parameter change transforms the access layer from a resistive element to a depleted region with negligible conductivity, thereby reducing on-resistance without compromising the Schottky barrier formation.
2Reliability
If high voltage-resistant structures like field plates are used, then voltage resistance increases, but parasitic capacitance increases which reduces operation speed
Solution Approach 1:
The invention converts the harmful effect of the AlGaN access layer (which would normally require field plates for voltage protection) into a beneficial depleted region. The p-type InGaN layer depletes the two-dimensional electron gas, creating a high-impedance region that provides inherent voltage resistance without the need for additional field plate structures, thus avoiding increased parasitic capacitance.
3Object-affected harmful factors
If the resistance of the access layer is decreased, then on-resistance decreases, but the structure becomes more complex
Solution Approach 1:
The p-type InGaN layer serves multiple functions simultaneously: it depletes the two-dimensional electron gas to reduce access layer resistance, provides inherent voltage resistance through the depleted region, and maintains the Schottky barrier formation capability. This multi-functionality achieves resistance reduction without adding structural complexity.
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 proposed diode structure achieves ultrahigh speed and high efficiency by drastically decreasing capacitance and lowering the forward turn-on voltage, enabling high-performance power reception and transmission systems.
Implementation Method 1
a two-dimensional electron gas is formed in the undoped GaN layer in the vicinity part of a hetero-interface between the AlxGa1-xN layer and the undoped GaN layer
Implementation Method 2
an anode electrode which is provided on the AlxGa1-xN layer and which is electrically connected to the metal electrode; and a cathode electrode which is provided on a part of the AlxGa1-xN layer
Data Source
AI summary
“This diode has an undoped GaN layer 11, an AlxGa1-xN layer (0<x<1) 12 thereon, a Mg-doped p-type InyGa1-yN layer (0<y<1) 13 having an island-like shape thereon, a metal electrode 14 thereon, an anode electrode 15 which is provided on the AlxGa1-xN layer 12 and which is electrically connected to the metal electrode 14 and a cathode electrode 16 which is provided on a part of the AlxGa1-xN layer 12 which is located on the opposite side from the anode electrode 15 with respect to the p-type InyGa1-yN layer 13. In this diode, at a non-operating time, a two-dimensional electron gas 17 is formed in the undoped GaN layer 11 in the vicinity part of a hetero-interface between the AlxGa1-xN layer 12 and the undoped GaN layer 11 except a part below the p-type InyGa1-yN layer 13.”