Nitride HEMT Polarization Layer for Gate-Edge Field Relief
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Solution Overview
Problem
High electron mobility transistors (HEMTs) using nitride semiconductors face challenges with high voltage applications, where the electric field intensity at the end portion of the gate electrode can exceed material limits, potentially leading to device breakdown.
Innovation Solution
Incorporating a polarization layer with an inclined Al composition between the gate and drain electrodes, where the Al composition decreases from the barrier layer side towards the opposite side, modulates the two-dimensional electron gas (2DEG) region and reduces electron concentration, thereby alleviating electric field concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional HEMT structure with barrier layer and channel layer is used, then high electron mobility is achieved, but electric field intensity at the gate electrode end portion exceeds material limits leading to device breakdown
Solution Approach 1:
The patent applies local quality by creating a polarization layer with spatially varying Al composition (decreasing from barrier layer side toward opposite side) specifically at the gate electrode end portion region. This localized compositional gradient modifies the 2DEG electron concentration only where needed to reduce electric field concentration, rather than uniformly across the entire device structure.
Solution Approach 2:
The patent changes the Al composition parameter within the polarization layer to create an inclined profile that decreases from the barrier layer side toward the opposite side. This parameter change modulates the polarization effect and 2DEG electron concentration, thereby reducing electric field intensity at the critical gate end portion without compromising overall device performance.
2Reliability
If the Al composition in the polarization layer is uniform, then manufacturing is simpler, but electric field concentration is not effectively reduced
Solution Approach 1:
The patent employs parameter changes by implementing an inclined Al composition profile in the polarization layer that decreases from the barrier layer side toward the opposite side. This gradient structure is achieved through controlled deposition processes that vary compositional parameters during fabrication, enabling effective electric field management while maintaining manufacturing feasibility.
3Reliability
If the polarization layer extends between both gate-source and gate-drain, then symmetry is maintained, but electric field concentration at the drain side is not specifically addressed
Solution Approach 1:
The patent applies asymmetry by positioning the polarization layer specifically between the gate electrode and the drain electrode, rather than symmetrically between gate-source and gate-drain. This asymmetric configuration directly addresses the electric field concentration problem at the drain side where it is most critical, optimizing device performance without unnecessary structural 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
The implementation of the polarization layer effectively reduces electric field concentration near the end portion of the gate electrode, preventing material breakdown and enabling the realization of high-withstand-voltage semiconductor devices.
Implementation Method 1
a polarization layer that is provided between the gate electrode and the drain electrode, from among between the gate electrode and the source electrode and between the gate electrode and the drain electrode on the second surface side of the barrier layer, includes a third nitride semiconductor that contains Al, and has an Al composition that decreases from the barrier layer side toward a third surface side opposite to the barrier layer side
Data Source
AI summary
a semiconductor device includes: a channel layer that includes a first nitride semiconductor; a barrier layer provided on a first surface side of the channel layer and includes a second nitride semiconductor; a source electrode and a drain electrode provided on a second surface side opposite to the channel layer side, of the barrier layer; a gate electrode provided between the source electrode and the drain electrode, on the second surface side of the barrier layer; and a polarization layer that is provided between the gate electrode and the drain electrode, from among between the gate electrode and the source electrode and between the gate electrode and the drain electrode on the second surface side of the barrier layer, includes a third nitride semiconductor that contains Al, and has an Al composition that decreases from the barrier layer side toward a third surface side opposite to the barrier layer side.