GaN HEMT Current Collapse Mitigation via P-type Layer
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Solution Overview
Problem
Nitride field effect transistors experience current collapse, leading to increased on-resistance when switching from off to on state, due to trapped electrons near the two-dimensional electron gas, which affects device reliability.
Innovation Solution
Incorporating a p-type nitride semiconductor layer between the gate and drain electrodes to inject holes into the nitride semiconductor layer, allowing trapped electrons to recombine and reducing current collapse, along with an n-type nitride semiconductor layer to maintain electron gas concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional AlGaN/GaN heterostructure is used to generate two-dimensional electron gas, then high electron concentration is achieved, but current collapse occurs causing increased on-resistance
Solution Approach 1:
A p-type nitride semiconductor layer is introduced as an intermediary between the gate electrode and drain electrode. This layer serves as a mediator to supply holes that neutralize trapped electrons in the depletion layer, thereby preventing current collapse while maintaining the beneficial two-dimensional electron gas channel.
Solution Approach 2:
The patent changes the electrical parameters of the nitride semiconductor layer by introducing p-type doping. This parameter change transforms the layer's ability to supply holes, enabling it to counteract the harmful effect of trapped electrons and prevent current collapse without compromising the electron gas concentration in the channel.
2Object-affected harmful factors
If holes are injected to neutralize trapped electrons, then current collapse is prevented, but electron gas concentration may decrease
Solution Approach 1:
The patent applies local quality by creating distinct regions with different doping types: the p-type nitride semiconductor layer is localized between the gate and drain to supply holes for neutralizing trapped electrons, while the undoped or differently doped nitride semiconductor layers maintain the two-dimensional electron gas concentration in the channel region. This spatial differentiation allows simultaneous achievement of both goals.
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
Effectively prevents or reduces current collapse, lowering on-resistance immediately after switching and maintaining low resistance even at low drain voltages, enhancing the reliability and performance of the field effect transistor.
Implementation Method 1
Incorporating a p-type nitride semiconductor layer between the gate and drain electrodes to inject holes into the nitride semiconductor layer, allowing trapped electrons to recombine and reducing current collapse
Implementation Method 2
two-dimensional electron gas (also expressed as '2DEG') is generated at its heterointerface due to spontaneous polarization and piezoelectric polarization
Implementation Method 3
two-dimensional electron gas (also expressed as '2DEG') is generated at its heterointerface due to spontaneous polarization and piezoelectric polarization
Implementation Method 4
by controlling a voltage applied to the gate electrode 7 to change the thickness of a depletion layer right under the gate electrode 7, the drain current can be controlled
Data Source
AI summary
A semiconductor device includes a field effect transistor that has a first nitride semiconductor layer and a second nitride semiconductor layer larger in bandgap than the first nitride semiconductor layer formed on a substrate in this order and a gate electrode, a source electrode, and a drain electrode, and uses two-dimensional electron gas formed at the interface between the first and second nitride semiconductor layers as the channel. The field effect transistor further has a p-type nitride semiconductor layer formed between the gate electrode and the drain electrode and electrically connected to the drain electrode.