Monolithic III-Nitride Transistor with Silicon Enable Switch
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Solution Overview
Problem
Depletion mode III-Nitride FETs used in power conversion circuits can potentially damage the load and circuit if the circuit powers up before the gate is biased to hold them in the off-state, due to their normally ON nature, and integrating these transistors is challenging for small devices.
Innovation Solution
A monolithic composite power device is created by integrating depletion mode III-Nitride transistors with an enhancement mode group IV switch, such as a silicon IGBT or FET, which acts as an enable switch to control the conduction path of the III-Nitride transistors, preventing premature power-up and providing protection during faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If depletion mode III-Nitride FETs are used in power conversion circuits, then high efficiency and high-voltage capability are achieved, but the load and circuit can be damaged if the circuit powers up before the gate is biased to hold them in the off-state
Solution Approach 1:
An enhancement mode group IV switch (silicon IGBT or FET) is introduced as an intermediary enable switch between the power source and the depletion mode III-Nitride FETs. This enable switch controls the conduction path and prevents premature power-up by ensuring the III-Nitride FETs are properly biased before conducting high voltage, thus resolving the contradiction between high-voltage capability and circuit protection.
2Loss of energy
If depletion mode III-Nitride FETs are used, then high current density with low resistive losses is achieved, but the normally ON nature creates risk of premature conduction
Solution Approach 1:
The enhancement mode group IV enable switch is configured to activate before the depletion mode III-Nitride FETs, establishing proper bias conditions in advance. This preliminary action ensures the III-Nitride FETs are in the desired off-state before high voltage is applied, preventing premature conduction while maintaining the low resistive losses characteristic of the depletion mode devices.
3Area of moving object
If small III-Nitride devices are integrated, then device size is reduced, but monolithic integration becomes more challenging
Solution Approach 1:
The patent employs a composite device structure combining group III-V (III-Nitride) and group IV (silicon) semiconductor materials on a single monolithic substrate. This composite approach enables the integration of both enhancement mode enable switches and depletion mode power FETs in a compact configuration, resolving the manufacturing challenges of integrating small devices while maintaining size reduction benefits.
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 integration prevents damage to the load and circuit by ensuring the III-Nitride transistors are properly biased, and allows for efficient monolithic integration of high voltage devices, reducing the risk of premature power-up and providing protection during system faults.
Implementation Method 1
III-Nitride and other group III-V HEMTs operate using polarization fields to generate a two-dimensional electron gas (2DEG) allowing for high current densities with low resistive losses.
Data Source
AI summary
There are disclosed herein various implementations of a monolithically integrated component. In one exemplary implementation, such a monolithically integrated component includes an enhancement mode group IV transistor and two or more depletion mode III-Nitride transistors. The enhancement mode group IV transistor may be implemented as a group IV insulated gate bipolar transistor (group IV IGBT). One or more of the III-Nitride transistor(s) may be situated over a body layer of the group IV IGBT, or the III-Nitride transistor(s) may be situated over a collector layer of the IGBT.