Nitride Gate Structure for Threshold Stability and Low Leakage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current nitride semiconductor devices face challenges in achieving stable threshold voltage and reducing gate leakage current due to the floating potential of the gate layer, leading to potential on-state errors and increased power loss.
Innovation Solution
The nitride semiconductor device incorporates a second gate electrode with a smaller contact area, made of a material with a higher work function, which forms an ohmic junction with the gate layer, and is positioned on an inactive region with a higher resistance, reducing the Schottky barrier and stabilizing the gate layer potential.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a gate layer containing acceptor impurity is provided on the electron supply layer to achieve normally-off operation, then the threshold voltage control is improved, but the gate layer potential becomes floating causing threshold voltage fluctuation and gate leakage current
Solution Approach 1:
A second gate electrode is introduced as an intermediary element between the first gate electrode and the gate layer. This second electrode serves as a potential reference that prevents the gate layer from floating, thereby stabilizing the threshold voltage and reducing gate leakage current without affecting the normally-off operation achieved by the acceptor-doped gate layer.
Solution Approach 2:
The gate electrode structure is segmented into two separate electrodes: a first gate electrode that contacts the gate layer for controlling the channel, and a second gate electrode that also contacts the gate layer but serves as a potential reference. This segmentation allows independent optimization of each electrode's function to simultaneously achieve normally-off operation and potential stabilization.
2Ease of operation
If the gate layer is made with acceptor impurity to eliminate the channel below the gate, then normally-off operation is achieved, but the device complexity increases due to additional gate electrode structure
Solution Approach 1:
The gate layer serves multiple functions: it contains acceptor impurity to enable normally-off operation by eliminating the channel, and simultaneously acts as a contact layer for both the first gate electrode (control function) and the second gate electrode (potential reference function). This multi-functionality reduces the need for additional separate structures.
Solution Approach 2:
The second gate electrode is merged with the gate layer contact structure, utilizing the same physical interface between the gate electrode and gate layer. This merging approach allows the potential reference function to be added without requiring completely separate structural elements, thereby minimizing the increase in device complexity.
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 suppresses the fluctuation of the threshold voltage and reduces gate leakage current, enhancing the device's operational stability and efficiency.
Implementation Method 1
a second gate electrode (52) made of a material different from the first gate electrode and in contact with the upper surface of the gate layer
Implementation Method 2
the gate layer raises a band energy of the conduction band near the heterojunction interface between the electron transit layer and the electron supply layer, so that a channel immediately below the gate layer disappears
Implementation Method 3
The HEMT uses a two-dimensional electron gas (2DEG) formed near an interface of a semiconductor heterojunction as a conductive path (channel)
Data Source
AI summary
A nitride semiconductor device includes an electron transit layer, an electron supply layer, a gate layer, a first gate electrode, a source electrode, a drain electrode, and a second gate electrode. The second gate electrode is made of a material different from the first gate electrode. The first gate electrode and the second gate electrode are in contact with an upper surface of the gate layer. A second contact area, which is a contact area between the second gate electrode and the gate layer, is smaller than a first contact area, which is a contact area between the first gate electrode and the gate layer.