HEMT Reverse Diode Gate Structure for Leakage Reduction
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Solution Overview
Problem
High electron mobility transistors (HEMTs) face challenges in achieving high frequency and high power performance due to limitations in electron mobility and source resistance, particularly in silicon-based semiconductor devices, which necessitate the use of group III-V semiconductor compounds like GaN for improved band gap and electron saturation velocity.
Innovation Solution
The development of HEMTs with a reverse diode gate or depletion structure, incorporating p-type and n-type doped group III nitride semiconductor layers, such as GaN, InGaN, AlGaN, and AlInN, with a gate electrode having a Schottky gate structure and an intermediate undoped group III nitride semiconductor layer, to enhance electron mobility and reduce gate leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If silicon-based semiconductor devices are used, then manufacturing is easier and cost is lower, but electron mobility is low and source resistance is high
Solution Approach 1:
The patent employs a heterostructure comprising multiple semiconductor material layers with different band gaps (e.g., GaN/AlGaN). This composite material approach enables the device to achieve high electron mobility through the formation of a 2DEG layer at the interface, while maintaining the manufacturability benefits of established semiconductor fabrication processes.
2Device complexity
If conventional gate structures are used, then device structure is simpler, but gate leakage is high and threshold voltage control is poor
Solution Approach 1:
The gate structure is segmented into multiple functional layers including a Schottky gate electrode, a barrier layer, and a reverse diode gate structure with p-type and n-type doped regions. This segmentation allows each layer to perform a specific function: the Schottky gate provides voltage control, the barrier layer blocks hole injection, and the reverse diode structure suppresses gate leakage, collectively achieving superior gate performance.
Solution Approach 2:
An intermediate undoped group III nitride semiconductor layer is introduced between the gate electrode and the channel-forming layers. This intermediary layer serves as a buffer that reduces stress at interfaces, controls carrier concentration, and prevents direct interaction between the gate electrode and the active channel, thereby reducing gate leakage while maintaining effective threshold voltage control.
3Reliability
If heterostructure with different band gap layers is used, then electron mobility increases through 2DEG formation, but device structure and manufacturing become more complex
Solution Approach 1:
The patent systematically varies key parameters of the heterostructure including band gap energy, layer thickness, and doping concentration across different semiconductor material layers. By optimizing these parameters, the device achieves high electron mobility through controlled 2DEG formation while managing structural complexity through deliberate parameter selection and gradient design.
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 increases the threshold voltage and reduces gate leakage, thereby improving the high-frequency and high-power performance of HEMTs by limiting hole injection and inducing a 2-dimensional electron gas (2DEG) region, enhancing the transistor's breakdown voltage and operational efficiency.
Implementation Method 1
a gate electrode having a Schottky gate structure
Implementation Method 2
a 2-dimensional electron gas (2DEG) layer may be induced in the semiconductor material layer having a smaller band gap than the other, and thus, mobility of electrons may be increased
Implementation Method 3
The gate structure includes a reverse diode gate structure and a gate electrode
Data Source
AI summary
A high electron mobility transistor (HEMT) according to example embodiments includes a first semiconductor layer, a second semiconductor layer on the first semiconductor layer, and a reverse diode gate structure on the second semiconductor layer. A source and a drain may be on at least one of the first semiconductor layer and the second semiconductor layer. A gate electrode may be on the reverse diode gate structure.