Group III-V HEMT Selectably Floating Substrate
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Solution Overview
Problem
III-Nitride and other group III-V high electron mobility transistors (HEMTs) suffer from performance degradation due to charge trapping, leading to increased dynamic on-resistance (d-Rdson) during pulsed applications, caused by charge centers in material layers and interfaces.
Innovation Solution
Implementing a group III-V HEMT with a selectably floating substrate, where the substrate is coupled to ground in the off-state and allowed to float in the on-state, reducing charge trapping and d-Rdson during pulsed operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the substrate is coupled to ground in the off-state, then device stability and charge control are improved, but dynamic on-resistance increases during pulsed operations due to charge trapping
Solution Approach 1:
The substrate coupling configuration is made dynamic rather than static. The substrate is coupled to ground during the off-state through a substrate contact, but is decoupled from ground during the on-state, allowing the electrical connection to change based on device operation phase. This dynamic configuration prevents charge trapping during pulsed operations while maintaining stability during idle periods.
Solution Approach 2:
The electrical state of the substrate is changed between two distinct parameters: grounded state during off-state and floating state during on-state. This parameter change allows the device to optimize performance for each operational phase, reducing charge trapping effects during high-stress pulsed operations while maintaining proper charge control during idle periods.
2Object-affected harmful factors
If the substrate is allowed to float during on-state, then dynamic on-resistance is reduced during pulsed operations, but device stability may be compromised in DC applications
Solution Approach 1:
The substrate electrical connection is made dynamic, switching between grounded and floating states based on device operation. During on-state, the substrate floats to minimize charge trapping and reduce dynamic on-resistance. During off-state, the substrate couples to ground to maintain stability. This dynamic adaptation resolves the contradiction between stability and resistance reduction.
Solution Approach 2:
The substrate coupling configuration alternates periodically with the device operation cycle. For pulsed operations, the substrate is grounded during off-periods and floats during on-periods. This periodic switching of the substrate electrical state allows the device to achieve low dynamic on-resistance during active periods while maintaining stability during idle periods.
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 configuration optimizes performance for direct current (DC) applications and significantly reduces or eliminates the increase in d-Rdson during pulsed operations, enhancing the reliability and efficiency of III-Nitride HEMTs.
Implementation Method 1
charge trapping may result from the presence of charge centers residing in the various material layers used to fabricate the HEMT, as well as at interfaces between those layers
Data Source
AI summary
There are disclosed herein various implementations of a group III-V high electron mobility transistor (HEMT) having a selectably floating substrate. Such a group III-V HEMT is situated over a substrate, and includes a transistor configured to selectably couple the substrate to ground and to selectably decouple the substrate from ground. The transistor is configured to ground the substrate when the group III-V HEMT is in an off-state and to cause the substrate to float when the group III-V HEMT is in an on-state.