GaN HEMT Field Plates for High Reverse-Bias Leakage Reduction
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Solution Overview
Problem
Current high-voltage high-electron mobility transistors (HEMTs) face challenges in withstanding high reverse-bias voltages and maintaining low leakage currents, which are crucial for high-frequency power electronics and microwave applications.
Innovation Solution
The development of high-voltage HEMTs using gallium-nitride material with specific structural configurations, including a gallium-oxide layer, gate-connected and source-connected field plates, and electrical isolation regions formed by ion implantation, to enhance breakdown voltage and reduce leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional HEMT structures are used, then device simplicity is maintained, but reverse-bias leakage current increases and breakdown voltage decreases
Solution Approach 1:
The device is segmented into multiple functional regions including gate-connected field plate, source-connected field plate, electrical isolation regions, and access regions. This segmentation allows each region to perform its specific function independently, achieving high breakdown voltage through distributed field management rather than a single complex structure.
Solution Approach 2:
Field plates are introduced as intermediary structures between the gate and drain, and between source and drain. These field plates act as mediators that redistribute the electric field, preventing direct high-field stress at critical interfaces and enabling higher breakdown voltage without proportionally increasing overall device complexity.
2Reliability
If reverse-bias voltage is increased, then high-voltage capability is improved, but leakage current increases
Solution Approach 1:
Electrical isolation regions are formed in advance in the access regions to preemptively block leakage current paths. By pre-establishing these isolation barriers before high reverse-bias voltage is applied, the device prevents leakage current generation rather than attempting to suppress it after occurrence, enabling high voltage capability without proportional leakage increase.
Solution Approach 2:
Different regions of the device are assigned different electrical properties: the field plates create high-field regions for voltage blocking, while the electrical isolation regions create low-conductivity regions for leakage suppression. This local differentiation of electrical quality allows simultaneous achievement of high breakdown voltage and low leakage current through region-specific optimization.
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
These HEMTs can withstand reverse-bias voltages exceeding 2000 volts with leakage currents as low as 40 microamps/mm, enabling efficient operation in high-frequency applications up to 30 GHz and resisting high-voltage transients.
Implementation Method 1
a gallium-oxide layer formed between the barrier layer and the gate
Implementation Method 2
electrical isolation regions formed by ion implantation
Implementation Method 3
gate-connected field plate electrically connected to the gate and extending beyond edges of the gate toward the drain and source
Data Source
AI summary
High-voltage, gallium-nitride HEMTs are described that are capable of withstanding reverse-bias voltages of at least 900 V and, in some cases, in excess of 2000 V with low reverse-bias leakage current. A HEMT may comprise a lateral geometry having a gate, a thin insulating layer formed beneath the gate, a gate-connected field plate, and a source-connected field plate.