Nitride FET Hole Injection for Current Collapse
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Solution Overview
Problem
Field effect transistors (FETs) using nitride semiconductors face a significant issue known as current collapse, where the current decreases over time due to trapped electrons in surface levels, making high-speed switching operations difficult, and existing protective films either fail to trap or eliminate these carriers effectively.
Innovation Solution
Incorporating a hole injection portion with a p-type third nitride semiconductor layer and a hole injection electrode, connected to the drain electrode, to inject holes that recombine with trapped electrons, thereby reducing current collapse by stabilizing the 2DEG layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a protective film (SiN film) is formed on the surface of the electron supply layer, then carrier trapping in surface levels is reduced, but trapped carriers cannot be eliminated and current collapse cannot be sufficiently reduced
Solution Approach 1:
A p-type semiconductor layer is introduced as an intermediary between the electron supply layer and the protective film. This p-type layer acts as a mediator that not only prevents carrier trapping at the interface but also actively eliminates trapped carriers through hole injection, thereby resolving the insufficient current collapse reduction achieved by protective films alone
Solution Approach 2:
The structure combines multiple materials with different properties: the n-type electron supply layer, the p-type semiconductor layer, and the protective film. This composite structure leverages the complementary properties of each material - the n-type layer provides high electron density, the p-type layer eliminates trapped carriers, and the protective film prevents surface trapping - to achieve superior current collapse reduction
2Reliability
If a p-type organic semiconductor film is used as protective film, then carrier trapping is limited and trapped carriers can be eliminated, but the film formation process is complex and the interface is unstable
Solution Approach 1:
The invention changes the material parameter from organic semiconductor to inorganic p-type semiconductor, and changes the formation method from complex vapor deposition or spin-off to standard semiconductor fabrication processes. This parameter change maintains the carrier elimination function while dramatically improving ease of manufacture and interface stability
3Reliability
If a p-type organic semiconductor film is used as protective film, then trapped carriers can be eliminated, but the interface between film and electron supply layer is unstable
Solution Approach 1:
The invention changes the material composition parameter from organic to inorganic semiconductor, which fundamentally improves interface stability. The inorganic p-type semiconductor forms a stable, well-defined interface with the n-type electron supply layer, eliminating the instability inherent in organic film interfaces while maintaining the trapped carrier elimination function
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 implementation of the hole injection portion effectively reduces current collapse by eliminating trapped electrons, enhancing the stability of the 2DEG layer and improving switching performance in nitride semiconductor FETs.
Implementation Method 1
a hole injection portion (141) formed on the semiconductor stack at a position closer to the drain electrode than to the gate electrode. The hole injection portion has a p-type third nitride semiconductor layer (142), and a hole injection electrode (143) formed on the third nitride semiconductor layer (142). Holes are injected from the hole injection portion into a 2DEG layer when the FET is turned on.
Implementation Method 2
The heterojunctions of the nitride semiconductors are characterized in that a high density two-dimensional electron gas (2DEG) layer is formed near the junction interface due to spontaneous polarization or piezoelectric polarization even in a non-doped state.
Implementation Method 3
The heterojunctions of the nitride semiconductors are characterized in that a high density two-dimensional electron gas (2DEG) layer is formed near the junction interface due to spontaneous polarization or piezoelectric polarization even in a non-doped state.
Data Source
AI summary
A field effect transistor includes a semiconductor stack formed on a substrate, and having a first nitride semiconductor layer and a second nitride semiconductor layer. A source electrode and a drain electrode are formed on the semiconductor stack so as to be separated from each other. A gate electrode is formed between the source electrode and the drain electrode so as to be separated from the source electrode and the drain electrode. A hole injection portion is formed near the drain electrode. The hole injection portion has a p-type third nitride semiconductor layer, and a hole injection electrode formed on the third nitride semiconductor layer. The hole injection electrode and the drain electrode have substantially the same potential.