GaN HEMT Charge Distribution Grid for Breakdown Voltage Control
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Solution Overview
Problem
Existing techniques for fabricating high voltage heterostructure field effect transistors (HFETs) for power switches result in breakdown voltages that are substantially below theoretical values, making it difficult to predict and achieve desired performance characteristics, requiring time-consuming cut-and-try methods rather than computer modeling.
Innovation Solution
A charge distribution grid is designed to redistribute electric charge in GaN HEMTs, compensating space charge to achieve higher breakdown voltages by forming a lateral conductive channel and drift region, with conductive components strategically placed between the gate and drain terminals to manage capacitance and electrostatic potential, ensuring even distribution and preventing current collapse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing fabrication techniques are used for HFETs, then the devices can be manufactured with current capabilities, but the breakdown voltages achieved are substantially below theoretical values
Solution Approach 1:
The patent applies preliminary action by introducing a charge distribution structure during the fabrication process that pre-establishes the desired electric field distribution and space charge compensation before the device operates. This allows the breakdown voltage to be controlled and predicted during design rather than requiring post-fabrication adjustments or cut-and-try methods.
Solution Approach 2:
The patent employs parameter changes by modifying the charge distribution parameters within the HFET structure, specifically by controlling the density and distribution of ionized donors and acceptors in the drift region. These parameter changes enable achievement of theoretical breakdown voltages while maintaining manufacturability.
2Manufacturing precision
If cut-and-try fabrication methods are used, then devices can be tested and adjusted, but the design process becomes time-consuming
Solution Approach 1:
The patent applies copying by using computer modeling to create a virtual representation of the HFET device with predicted performance characteristics. The charge distribution structure parameters are optimized through modeling before fabrication, allowing the physical device to be a direct implementation of the modeled design rather than requiring iterative cut-and-try adjustments.
Solution Approach 2:
The patent performs preliminary design optimization through computer modeling and simulation before actual fabrication. The charge distribution structure is designed in advance with calculated parameters that predict the desired breakdown voltage, eliminating the need for time-consuming iterative testing and adjustment cycles.
3Manufacturing precision
If field plates are used to influence breakdown voltage, then voltage control is attempted, but the influence on breakdown voltage is difficult to predict
Solution Approach 1:
The patent applies feedback by incorporating space charge compensation mechanisms that respond to and counteract electric field variations in the drift region. The charge distribution structure provides feedback control over the electric field distribution, ensuring predictable breakdown voltage characteristics rather than relying on the unpredictable influence of field plates.
Solution Approach 2:
The patent uses computer modeling to accurately predict and understand the influence of charge distribution structures on breakdown voltage. This modeling capability provides predictability that is not achieved with field plates, allowing designers to know in advance how the structure will influence voltage characteristics.
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 approach allows for the design of power HFETs with predictable breakdown voltages, enabling faster state transitions and improved reliability by maintaining high breakdown voltages and controlling current dispersion, thus enhancing the efficiency and speed of power switching operations.
Implementation Method 1
A charge distribution grid is designed to redistribute electric charge in GaN HEMTs, compensating space charge to achieve higher breakdown voltages
Implementation Method 2
with conductive components strategically placed between the gate and drain terminals to manage capacitance and electrostatic potential
Data Source
AI summary
A semiconductor device includes a substrate and a first active layer disposed over the substrate. The semiconductor device also includes a second active layer disposed on the first active layer such that a lateral conductive channel arises between the first active layer and the second active layer. a source, gate and drain contact are disposed over the second active layer. A conductive charge distribution structure is disposed over the second active layer between the gate and drain contacts. The conductive charge distribution structure is capacitively coupled to the gate contact.