HEMT Active Layer Structure for Lower Current Collapse
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Solution Overview
Problem
High Electron Mobility Transistors (HEMTs) face issues with charge trapping at the drain side of the gate, leading to current collapse and increased interface trap density under high-voltage operation, which results in linear drain current degradation and high on-resistance.
Innovation Solution
A III-V HEMT structure is developed with a high Al diffusion layer formed by diffusing Al atoms from a thin AlN film into the active layer, reducing interface trap density and current collapse through a high temperature annealing process, thereby improving the linear drain current degradation and dynamic on-state resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If HEMT structure operates under high-voltage conditions, then power application performance is improved, but charge trapping at the drain side of the gate occurs leading to current collapse
Solution Approach 1:
A barrier layer is formed at the drain side of the gate before high-voltage operation occurs. This preliminary structural preparation prevents charge trapping and current collapse by creating a protective interface that blocks charge accumulation, allowing the HEMT to maintain reliable operation under high-voltage power conditions
Solution Approach 2:
The barrier layer acts as an intermediary structure between the gate and the underlying layers. It mediates the interaction by providing a controlled interface that prevents direct charge trapping at the drain side, thereby eliminating current collapse while preserving the high-power performance of the HEMT
2Power
If HEMT structure operates under high-voltage conditions, then power application performance is improved, but interface trap density increases leading to linear drain current degradation
Solution Approach 1:
The barrier layer is formed in advance at the critical interface region before operation. This preliminary action prevents interface trap formation and accumulation during high-voltage operation, thereby preventing linear drain current degradation while maintaining power performance
Solution Approach 2:
The barrier layer serves as an intermediary that protects the interface between different material layers. It prevents direct interaction that would create interface traps, thereby maintaining low interface trap density and preventing drain current degradation during high-power operation
3Power
If HEMT structure operates under high-voltage conditions, then power application performance is improved, but on-resistance increases
Solution Approach 1:
The barrier layer is prepared in advance to create optimized charge distribution and electric field profiles. This preliminary structural configuration maintains low on-resistance by preventing charge trapping that would otherwise increase resistance during high-voltage power operation
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 high Al diffusion layer effectively reduces interface trap density and current collapse, leading to improved reliability and performance by minimizing electron trapping at the interface, resulting in lower on-state resistance and reduced linear drain current degradation.
Implementation Method 1
a high Al diffusion layer formed by diffusing Al atoms from a thin AlN film into the active layer
Implementation Method 2
through a high temperature annealing process
Data Source
AI summary
A semiconductor structure includes: a channel layer; an active layer over the channel layer, wherein the active layer is configured to form a two-dimensional electron gas (2DEG) to be formed in the channel layer along an interface between the channel layer and the active layer; a gate electrode over a top surface of the active layer; and a source/drain electrode over the top surface of the active layer; wherein the active layer includes a first layer and a second layer sequentially disposed therein from the top surface to a bottom surface of the active layer, and the first layer possesses a higher aluminum (Al) atom concentration compared to the second layer. An HEMT structure and an associated method are also disclosed.