InGaN Back-Barrier Composition Gradient for HEMT Leakage Suppression
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Solution Overview
Problem
Nitride semiconductor devices, particularly high electron mobility transistors (HEMTs), face challenges in suppressing short channel effects and drain leakage currents due to the difficulty in reducing leakage currents effectively, especially at high voltage operations, despite the use of back-barrier layers.
Innovation Solution
A nitride semiconductor device with a back-barrier layer having a composition gradient where the In composition increases at one interface and continuously reduces towards the other, enhancing the confinement effect and reducing leakage currents by increasing the conduction band potential, thereby effectively suppressing short channel effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a back-barrier layer is used to reduce leakage current, then drain leakage current is reduced, but short channel effect is not sufficiently suppressed
Solution Approach 1:
The back-barrier layer is designed with a composition gradient where the indium composition ratio varies through the thickness direction. Specifically, the indium composition ratio increases from the interface with the first nitride semiconductor layer toward the interface with the second nitride semiconductor layer. This local variation in composition creates different barrier heights at different locations, achieving both leakage current reduction and short channel effect suppression simultaneously.
Solution Approach 2:
The invention changes the compositional parameter of the back-barrier layer by introducing a gradient in indium composition ratio. Instead of a uniform composition, the indium content varies continuously or stepwise through the layer thickness, transforming the barrier properties to achieve both desired functions: reducing leakage current while suppressing short channel effects in high voltage operations.
2Quantity of substance
If In-based nitride semiconductor is used for electron supply layer, then two-dimensional electron gas density is increased, but leakage current increases
Solution Approach 1:
The back-barrier layer acts as an intermediary structure between the first nitride semiconductor layer and the second nitride semiconductor layer. By positioning this layer with appropriate indium composition gradient at the interface region, it provides an additional barrier to leakage current while allowing the In-based electron supply layer to maintain its high two-dimensional electron gas density in the active channel region.
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 composition gradient in the back-barrier layer achieves sufficient suppression of short channel effects and reduces current collapse, improving the pinch-off characteristic and reliability of the nitride semiconductor device.
Implementation Method 1
a HEMT using a nitride semiconductor which may generate highly-concentrated two-dimensional electron gases having high piezoelectric polarization and spontaneous polarization
Implementation Method 2
a HEMT using a nitride semiconductor which may generate highly-concentrated two-dimensional electron gases having high piezoelectric polarization and spontaneous polarization
Data Source
AI summary
A nitride semiconductor device includes a first nitride semiconductor layer; a back-barrier layer that contains InGaN provided on the first nitride semiconductor layer; and a second nitride semiconductor layer that is provided on the back-barrier layer, wherein, in the back-barrier layer, in a thickness direction, an In composition increases at a first interface with the first nitride semiconductor layer, and the In composition is continuously reduced toward a second interface with the second nitride semiconductor layer.