GaN Schottky Diode InGaN Interlayer Breakdown Voltage
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Solution Overview
Problem
The challenge is to enhance the breakdown voltage of GaN-based Schottky barrier diodes while minimizing the on-resistance and forward voltage, which is hindered by the tradeoff between the work function of the anode electrode and backward breakdown voltage, and the difficulty in activating Mg-doped p-type GaN layers, leading to reduced crystallinity and increased roughness.
Innovation Solution
Incorporating an InGaN layer or a nitride semiconductor layer with a larger band gap, such as AlN, between the anode electrode and the GaN layer to increase the band potential and improve backward breakdown voltage without the need for high Mg doping, thereby avoiding the issues of crystallinity reduction and surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the work function of the anode electrode is lowered to reduce on-resistance and forward voltage, then on-resistance and forward voltage are reduced, but backward breakdown voltage is lowered
Solution Approach 1:
An InGaN layer is introduced as an intermediary layer between the anode electrode and the n-type GaN layer. This intermediate layer modifies the band alignment and electrical characteristics at the interface, enabling the system to achieve low on-resistance and forward voltage while maintaining high backward breakdown voltage, thus resolving the tradeoff between these parameters
Solution Approach 2:
The invention changes the material composition parameter by using InGaN (with varying In content) instead of conventional materials. By adjusting the In content in the InGaN layer, the band gap and electrical properties can be optimized to simultaneously achieve low on-resistance/forward voltage and high breakdown voltage
2Reliability
If a large amount of Mg is doped to sufficiently secure activated Mg, then activated Mg is sufficient, but crystallinity of the p-type GaN layer is reduced and surface roughness increases
Solution Approach 1:
The invention extracts and removes the problematic p-type GaN layer containing Mg dopant from the device structure. Instead of using Mg-doped p-type GaN, the patent employs an InGaN layer that does not require high-concentration doping, thereby eliminating the issues of reduced crystallinity and increased surface roughness associated with heavy Mg doping
Solution Approach 2:
The invention replaces the complex, problematic p-type GaN layer (requiring high Mg doping and high-temperature annealing) with a simpler InGaN layer that can be formed without excessive doping. This substitution eliminates the need for complex activation annealing processes and avoids the degradation of crystallinity and surface quality
3Reliability
If activation annealing is performed at 1000°C or higher to activate Mg, then Mg activation is sufficient, but surface roughness of the Schottky surface is increased and yield is reduced
Solution Approach 1:
The invention eliminates the need for high-temperature activation annealing by replacing the Mg-doped p-type GaN layer with an InGaN layer. This substitution removes the requirement for aggressive thermal processing, thereby preventing surface roughness formation and maintaining high device yield
4Ease of manufacture
If dry etching is performed to pattern the p-type GaN layer, then the Schottky surface is exposed, but roughness of the p-type GaN layer and Schottky surface is caused
Solution Approach 1:
The invention removes the p-type GaN layer that requires dry etching for patterning. By replacing it with an InGaN layer that serves the same functional purpose without requiring aggressive etching, the patent avoids the generation of surface roughness while maintaining ease of manufacture
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 approach effectively increases the backward breakdown voltage while maintaining low on-resistance and forward voltage, simplifying the manufacturing process and improving device yield by eliminating the need for high-temperature activation annealing and reducing the risk of surface damage during dry etching.
Implementation Method 1
a nitride semiconductor layer containing Al, having a band gap larger than that of GaN
Data Source
AI summary
A semiconductor device is provided with: a GaN layer; an anode electrode that forms a Schottky junction with a Ga face of the GaN layer; and an InGaN layer positioned between at least a part of the anode electrode and the GaN layer.