Compound Semiconductor Device With Channel Modifier
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Solution Overview
Problem
Compound semiconductor devices with two-dimensional carrier gas channels face challenges in minimizing leak current, particularly in maintaining a normally-off state to ensure safe operation and prevent current leakage.
Innovation Solution
A compound semiconductor device is designed with a hetero junction between a first active layer and a second active layer, featuring a channel modifier that locally changes the channel into a normally-off state by modifying the band structure, thereby preventing current leakage and ensuring safe operation. The device includes a first electrode and a second electrode in ohmic contact with the first active layer, and a channel modifier on the second active layer that encloses but is isolated from the electrodes, effectively suppressing leak current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a hetero junction is formed to generate a two-dimensional carrier gas channel, then electron mobility is improved, but leak current increases and the device cannot maintain a normally-off state
Solution Approach 1:
The patent applies local quality by forming a channel modifier layer in specific regions to create normally-off characteristics. The channel modifier is formed only in predetermined regions where normally-off characteristics are needed, while other regions maintain high electron mobility for fast operation. This spatial differentiation of properties resolves the contradiction between speed and reliability.
Solution Approach 2:
The patent segments the channel into different functional regions: regions with channel modifier for normally-off operation and regions without channel modifier for high-speed operation. This segmentation allows the device to simultaneously achieve low leak current in critical areas and high electron mobility in active areas, resolving the technical contradiction.
2Reliability
If the channel is modified to achieve normally-off state, then leak current is suppressed, but device complexity increases due to additional channel modifier structure
Solution Approach 1:
The patent merges the channel modifier formation with existing device fabrication processes. The channel modifier is formed using the same epitaxial growth process that creates the hetero junction layers, integrating the normally-off functionality into the standard manufacturing flow without requiring entirely separate process steps, thus limiting the increase in device complexity.
Solution Approach 2:
The channel modifier acts as an intermediary layer between the hetero junction and the substrate/surroundings. This intermediary structure enables normally-off characteristics by modifying the local band structure without fundamentally changing the core hetero junction design, achieving reliability improvement with minimal added 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 solution effectively suppresses leak current and ensures safer operation by maintaining a normally-off state, preventing current flow until a positive bias is applied, thus enhancing the reliability and efficiency of the device.
Implementation Method 1
a hetero junction of compound semiconductors so as to generate a two-dimensional electron gas
Implementation Method 2
a quantum well is formed in the GaAs layer along the hetero junction
Implementation Method 3
Abundant electrons supplied by the AlGaAs layer to the quantum well forms a two-dimensional electron gas
Implementation Method 4
a channel modifier for locally changing a part of the first active layer under the channel modifier into a normally-off state
Data Source
AI summary
A compound semiconductor device is comprised of: a compound semiconductor layer including a first active layer and a second active layer forming a hetero junction with the first active layer so as to naturally generate a two-dimensional carrier gas channel in the first active layer along the hetero junction; a first electrode formed on the second active layer; a second electrode in ohmic contact with the first active layer and isolated from the first electrode; and a channel modifier for locally changing a part of the first active layer under the channel modifier into a normally-off state, the channel modifier being formed on the second active layer so as to enclose but be isolated from the first electrode and the second electrode.