Enhancement Mode HEMT Carrier Providing Layer Design
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Solution Overview
Problem
Enhancement mode high electron mobility transistor (HEMT) devices face challenges in achieving high output current and efficient device performance due to limitations in carrier concentration and epitaxial growth flexibility.
Innovation Solution
A carrier providing layer with a higher aluminum content than the barrier layer is disposed on the sidewall of the P-type semiconductor layer, extending laterally, and can have a single-layer or multi-layer structure, with the option of being in contact with the barrier or channel layer, to enhance carrier concentration and output current, and a dielectric layer is optionally included between the gate electrode and the P-type semiconductor layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a conventional HEMT structure is used, then the device structure is simple, but the output current is limited due to insufficient carrier concentration
Solution Approach 1:
The device is segmented into distinct functional layers: a barrier layer for carrier confinement, a P-type semiconductor layer for electric field control, and a carrier providing layer for enhanced carrier supply. This segmentation allows each layer to independently contribute to the overall carrier concentration without increasing overall structural complexity
Solution Approach 2:
The carrier providing layer is nested within the existing HEMT structure, positioned between the barrier layer and the gate electrode. This nested configuration allows the carrier providing layer to integrate seamlessly with the conventional HEMT architecture while enhancing carrier concentration, effectively adding functionality without proportionally increasing complexity
2Quantity of substance
If the aluminum content in the barrier layer is increased to enhance carrier concentration, then the output current increases, but the breakdown voltage decreases
Solution Approach 1:
Different aluminum contents are assigned to different layers: the barrier layer has a controlled aluminum content for carrier confinement, while the carrier providing layer has a higher aluminum content specifically in the region near the gate electrode to enhance carrier concentration. This local differentiation allows optimization of each layer's function without compromising overall device reliability
Solution Approach 2:
The carrier providing layer is positioned in a specific spatial dimension between the barrier layer and gate electrode, creating a three-dimensional carrier concentration gradient. This dimensional approach allows enhanced carrier supply near the gate without uniformly increasing aluminum content throughout the barrier layer, thereby maintaining breakdown voltage
3Speed
If the gate electrode is made smaller to improve switching speed, then the switch speed increases, but the output current decreases
Solution Approach 1:
The carrier providing layer acts as a carrier reservoir that continuously supplies carriers to the channel region, effectively copying or replenishing carriers that would otherwise be limited by the small gate electrode size. This carrier copying mechanism maintains high output current despite the reduced gate dimensions needed for fast switching
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 configuration effectively increases the output current and improves device performance by enhancing carrier concentration and reducing resistance, while simplifying the process steps and increasing the flexibility of epitaxial growth and device design.
Implementation Method 1
a carrier providing layer is disposed on the barrier layer or the channel layer outside of the gate region, so as to effectively increase the output current
Implementation Method 2
enhancing carrier concentration and reducing resistance
Data Source
AI summary
Provided is an enhancement mode HEMT device including a substrate, a channel layer, a barrier layer, a P-type semiconductor layer, a carrier providing layer, a gate electrode, a source electrode and a drain electrode. The channel layer is disposed on the substrate. The barrier layer is disposed on the channel layer. The P-type semiconductor layer is disposed on the barrier layer. The carrier providing layer is disposed on the sidewall of the P-type semiconductor layer and extends laterally away from the P-type semiconductor layer. The gate electrode is disposed on the P-type semiconductor layer. The source electrode and the drain electrode are disposed on the carrier providing layer and at two sides of the gate electrode. A method of forming an enhancement mode HEMT device is further provided.