GaN Diode Anode Metal Crystal Orientation for Low Turn-On Voltage
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Solution Overview
Problem
GaN diodes exhibit high turn-on voltage due to the large Schottky barrier resulting from the work function difference between GaN and metal, limiting their efficiency in low-power rectification and other applications.
Innovation Solution
A low turn-on voltage GaN diode with an anode metal having a consistent crystal orientation, utilizing a tungsten (W) or molybdenum (Mo) metal contact with a specific crystal orientation, is developed, along with a method involving a substrate layer, GaN buffer and channel layers, an AlGaN barrier layer, and a dielectric layer, to reduce the Schottky barrier and turn-on voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional Pt and AlGaN layer are used to achieve Schottky contact, then the device structure is simple, but the turn-on voltage is more than 1 V due to high Schottky barrier
Solution Approach 1:
The patent changes the crystal orientation parameter of the anode metal from random or mixed orientation to a specific consistent orientation (such as <100> or <110>). This parameter change optimizes the work function matching between the metal and GaN, thereby reducing the Schottky barrier height and lowering the turn-on voltage below 1 V while maintaining structural simplicity
Solution Approach 2:
The patent employs a composite metal structure combining a base metal layer (Pt, AlGaN, or other materials) with an anode metal layer having specific crystal orientation. This composite structure leverages the advantages of both materials: the base layer provides structural support and the oriented metal layer provides optimized electrical contact with reduced Schottky barrier
2Reliability
If GaN material is used in diode devices, then the device has large band gap and high breakdown field strength, but the Schottky barrier is high due to work function difference between GaN and metal
Solution Approach 1:
The patent modifies the crystal orientation parameter of the anode metal to achieve optimal work function matching with GaN material. This parameter optimization reduces the Schottky barrier height at the metal-GaN interface, enabling lower turn-on voltage while preserving the high breakdown field strength inherent to GaN devices
Solution Approach 2:
The patent applies local quality optimization at the metal-GaN contact interface by using an anode metal with specific crystal orientation. This localized optimization addresses the work function mismatch issue at the critical contact region without changing the bulk properties of the GaN material, thereby maintaining high breakdown field strength while reducing turn-on voltage
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 consistent crystal orientation of the anode metal improves work function matching, forming a Schottky contact with a smaller barrier, resulting in a lower turn-on voltage and reduced lattice mismatch, enhancing the diode's performance.
Implementation Method 1
the Schottky barrier of the device is high due to the large difference of the work function between GaN material and metal
Implementation Method 2
the consistent crystal orientation of the anode metal improves work function matching, forming a Schottky contact with a smaller barrier, resulting in a lower turn-on voltage and reduced lattice mismatch
Data Source
AI summary
A low turn-on voltage GaN diode having an anode metal with a consistent crystal orientation and a preparation method thereof. The low turn-on voltage GaN diode having an anode metal with a consistent crystal orientation provided by the present disclosure includes a substrate layer, a GaN buffer layer, a GaN channel layer and an AlGaN barrier layer, which are arranged in sequence from bottom to top; a cathode arranged on the AlGaN barrier layer; a groove arranged in the GaN channel layer and the AlGaN barrier layer, and an anode provided on a bottom and a side wall of the groove and part of the AlGaN barrier layer; a dielectric layer provided on an uncovered portion of the AlGaN barrier layer; wherein, a contact portion of the anode with the groove and the AlGaN barrier layer is W or Mo metal with a crystal orientation of <100>.