p-FET-Like Field Effect Transistor With High Current Density
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Solution Overview
Problem
Conventional p-FET transistors have significantly lower current density due to low hole mobility in p-GaN layers, requiring larger active surfaces to match n-FET performance, increasing costs and complexity in complementary logic circuits.
Innovation Solution
A field effect transistor design featuring a substrate with an electron channel layer, a barrier layer, a hole channel layer, and a p-type doped semiconductor layer, where the p-type doped layer allows injection of holes to form a conduction channel between source and drain electrodes, mimicking p-FET behavior with electron-based conduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional p-FET transistor is designed with a p-GaN layer to achieve p-channel conduction, then the transistor exhibits p-FET behavior, but the current density is about 100 times lower than that of an n-FET transistor due to low hole mobility
Solution Approach 1:
A thin aluminum nitride (AlN) interfacial layer is inserted between the p-GaN layer and the AlGaN barrier layer. This intermediary layer prevents hole accumulation at the interface while allowing the p-GaN layer to maintain its p-channel conduction behavior, thereby resolving the contradiction between achieving p-FET behavior and maintaining high current density
Solution Approach 2:
The invention changes the structural parameters of the transistor by introducing the AlN interfacial layer with specific thickness (5-50 nm) and modifying the doping concentration in the p-GaN layer. These parameter changes enable the system to achieve both p-FET behavior and high current density by optimizing the hole transport properties
2Productivity
If the active area of a p-FET transistor is increased to compensate for low hole mobility, then the current carrying capacity matches that of an n-FET transistor, but the cost and device complexity increase
Solution Approach 1:
By changing the doping concentration parameters in the p-GaN layer and optimizing the thickness parameters of the AlN interfacial layer and AlGaN barrier layer, the invention achieves high current density in a compact device structure, eliminating the need for large active areas while maintaining current carrying capacity
3Ease of operation
If a p-GaN layer is used to form a hole conduction channel, then the transistor can operate as a p-FET, but the low hole mobility results in significantly reduced current density compared to electron conduction in n-FET
Solution Approach 1:
The AlN interfacial layer acts as a mediator that modifies the interface properties between p-GaN and AlGaN, preventing harmful hole accumulation while preserving p-channel conduction, thus maintaining ease of operation with improved current density
Solution Approach 2:
The invention uses a composite structure combining p-GaN, AlN, and AlGaN layers, where each material contributes specific properties: p-GaN provides hole conduction, AlN prevents hole accumulation, and AlGaN forms the barrier, together achieving both p-channel operation and high current density
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 design achieves a current density comparable to n-FET transistors, reducing the need for larger active surfaces and lowering costs while maintaining high switching speed and voltage withstand capabilities.
Implementation Method 1
The ohmic contact between the second portion of the source electrode and the p-type doped semiconductor material layer allows the injection of free holes into the hole channel layer when a negative voltage is applied between the gate electrode and the source electrode
Implementation Method 2
These holes attract free electrons to the interface between the electron channel layer and the barrier layer, thus forming a conduction channel between the source electrode and the drain electrode
Implementation Method 3
The HEMT transistor supports high on-state current densities due to the high charge carrier density and high carrier mobility in the two-dimensional electron gas
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to a field-effect transistor (2) comprising: - a substrate (21); - an electron channel layer (22) disposed on the substrate (21); - a barrier layer (23) disposed on the electron channel layer (22); - a hole channel layer (24) disposed on the barrier layer (23); - a p-type doped semiconductor material layer (25) disposed on the hole channel layer (24); - a source electrode (27) comprising a first portion (27a) in ohmic contact with the electron channel layer (22) and a second portion (27b) in ohmic contact with the p-type doped semiconductor material layer (25); - a drain electrode (28) in ohmic contact with the electron channel layer (22); - a grid electrode (29) disposed opposite the layer of p-type doped semiconductor material (25), between the source and drain electrodes (27-28).