Nitride Semiconductor Buffer Layer Doping for Leak Current Reduction
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Solution Overview
Problem
Conventional nitride semiconductor devices face issues with lateral leak paths and increased leak current due to lattice constant differences between AlN and GaN layers, which are not adequately addressed by existing buffer layer configurations, leading to poor ON resistance and current collapse.
Innovation Solution
A nitride semiconductor device with a buffer layer comprising composite layers of nitride semiconductor layers with different lattice constants, where at least one layer is doped with carbon and oxygen atoms in the carrier region to compensate for 2-dimensional electron gas carriers, reducing lattice constant-induced leak currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a buffer layer with composite layers of AlN and GaN is used to decrease distortion from thermal expansion and lattice constant differences, then the structural stability is improved, but 2-dimensional electron gas carriers are generated at the interfaces due to lattice constant differences, causing increased leak current
Solution Approach 1:
An AlGaN layer is introduced as an intermediary layer between the AlN layer and the GaN layer. This intermediate layer has a lattice constant that is intermediate between AlN and GaN, thereby reducing the lattice constant difference at the interfaces and suppressing the generation of 2-dimensional electron gas carriers that cause leak current
Solution Approach 2:
The lattice constant parameter is gradually changed by introducing an AlGaN layer with intermediate composition between AlN and GaN. This gradual parameter transition reduces the abrupt lattice mismatch at interfaces, thereby reducing carrier generation and leak current while maintaining the buffer layer's ability to compensate thermal expansion and lattice constant differences
2Object-generated harmful factors
If impurities such as carbon or transitional metals are added to the GaN layer to increase resistance and decrease leak current, then the leak current is reduced, but cracks appear in the epitaxial layer and dislocation density increases, lowering electron mobility
Solution Approach 1:
Different regions of the buffer layer are given different properties: the AlGaN layer is designed with specific composition and thickness to suppress carrier generation at interfaces, while the GaN layer maintains high crystal quality for electron transport. This local differentiation allows leak current reduction without compromising electron mobility
Solution Approach 2:
The AlGaN layer serves as a mediator that reduces the need for high impurity concentrations in the GaN layer. By suppressing carrier generation at the AlN/GaN interface, the AlGaN layer allows the GaN layer to maintain lower impurity levels, thereby avoiding crack formation and dislocation while still reducing leak current
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 simultaneous doping of carbon and oxygen atoms in the carrier region effectively decreases leak current by stabilizing the system and compensating 2-dimensional electron gas levels, resulting in improved ON resistance and breakdown voltage.
Implementation Method 1
at least one of the one or more composite layers is doped with carbon atoms and oxygen atoms in at least a portion of a carrier region
Implementation Method 2
the lattice constant difference between the AlN layer and the GaN layer causes 2-dimensional electron gas carriers to occur in the buffer layer
Data Source
AI summary
Provided is a nitride semiconductor device comprising a base substrate; a buffer layer formed above the base substrate; an active layer formed on the buffer layer; and at least two electrodes formed above the active layer. The buffer layer includes one or more composite layers that each have a plurality of nitride semiconductor layers with different lattice constants, and at least one of the one or more composite layers is doped with carbon atoms and oxygen atoms in at least a portion of a carrier region of the nitride semiconductor having the largest lattice constant among the plurality of nitride semiconductor layers, the carrier region being a region in which carriers are generated due to the difference in lattice constants between this nitride semiconductor layer and the nitride semiconductor layer formed directly thereon.