Recessed-Barrier HEMT Structure for High Drive Current
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Solution Overview
Problem
Existing high electron mobility transistors (HEMTs) face challenges in achieving high drive current and reducing leakage current, which limits their performance.
Innovation Solution
The HEMT structure includes a substrate, multiple buffer and barrier layers, a doped structure, a spacer, and insulating layer, with specific materials like gallium nitride and aluminum gallium nitride, forming a two-dimensional electron gas (2DEG) and a gate electrode configuration to enhance electron mobility and reduce leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional HEMT structures are used, then device simplicity is maintained, but drive current is insufficient and leakage current is high
Solution Approach 1:
The transistor structure is divided into multiple functional segments including a first barrier layer, a second barrier layer with recessed portion, a doped structure, and a gate electrode with specific configuration. Each segment performs a specific function in controlling electron flow, enabling high drive current while maintaining manageable complexity through functional specialization.
Solution Approach 2:
Different regions of the transistor are given different doping types and concentrations - the doped structure has specific doping while other regions remain undoped or have different doping characteristics. The second barrier layer has a recessed portion creating localized variations in material properties, optimizing electron transport in specific areas while maintaining overall device performance.
2Reliability
If conventional HEMT structures are used, then manufacturing process is simple, but leakage current reduction is insufficient
Solution Approach 1:
The doped structure is formed before the second barrier layer, and the second barrier layer is formed with a recessed portion that exposes part of the doped structure. This preliminary configuration of doping and barrier layer formation creates built-in electric field distributions that suppress leakage current before the device operates, improving reliability without requiring additional complex manufacturing steps.
Solution Approach 2:
The gate electrode is positioned within the spacer structure and extends partially into the upper portion of the second barrier layer, creating a nested configuration where the gate is embedded in multiple layers. This nested arrangement provides multiple barriers to leakage current paths while maintaining a compact structure that is manufacturable with standard semiconductor processing techniques.
3Speed
If simple barrier layer configuration is used, then manufacturing is easier, but electron mobility is insufficient
Solution Approach 1:
The second barrier layer is formed with a recessed portion that creates localized variations in barrier thickness and composition. This parameter variation in the barrier layer structure optimizes the potential profile for electron transport, enhancing electron mobility in the channel region while the overall barrier layer configuration remains manufacturable with standard semiconductor processes.
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 proposed structure improves drive current and reduces leakage current, enhancing the overall performance of the HEMT.
Implementation Method 1
forming a two-dimensional electron gas (2DEG) and a gate electrode configuration to enhance electron mobility
Implementation Method 2
The first barrier layer may comprise aluminum gallium nitride. The second barrier layer may comprise aluminum gallium nitride
Data Source
AI summary
A High-Electron-Mobility-Transistor having a first barrier layer formed on a first buffer layer formed on a substrate. A second barrier layer having a recessed portion and an upper portion formed over the first barrier layer. A doped structure formed on the first barrier layer and surround by the second barrier layer. A second buffer layer formed over the recessed portion and the upper portion of the second barrier layer. A spacer formed on a portion of the doped structure. An insulating layer formed over the second buffer layer. A gate electrode formed within the spacer through the insulating layer, through the second buffer layer and partially into the upper portion of the second barrier layer. A drain terminal formed at a first side of the gate electrode. A source terminal formed at a second side of the gate electrode.