Vertical GaN MISFET Dual-Material Trench Electrode
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing GaN devices with lateral structures are not suitable for high-current power devices and lack sufficient breakdown voltage, and achieving ohmic contact with both P-type and N-type group III-V nitride semiconductor layers is challenging, making it difficult to implement a normally-off operation.
Innovation Solution
A vertical MIS field-effect transistor is designed with a stacked N-type GaN drain layer, P-type GaN layer, and N-type GaN source layer, using a source electrode with a first conductive material for P-type GaN and a second conductive material for N-type GaN, both embedded in a trench, to establish excellent ohmic contact and enable normally-off operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single conductive material is used for the electrode, then the device structure is simple, but it cannot achieve excellent ohmic contact with both P-type and N-type group III-V nitride semiconductor layers
Solution Approach 1:
The electrode is divided into two distinct portions: a first electrode portion made of a first conductive material that contacts the P-type group III-V nitride semiconductor layer, and a second electrode portion made of a second conductive material that contacts the N-type group III-V nitride semiconductor layer. This segmentation allows each portion to be optimized for its specific contact requirement, achieving excellent ohmic contact with both layer types simultaneously.
2Reliability
If a lateral structure is used for the GaN device, then the device fabrication is straightforward, but the breakdown voltage is insufficient for high-current power devices
Solution Approach 1:
The invention transitions from a conventional lateral structure to a vertical structure. The first and second group III-V nitride semiconductor layers are stacked vertically, with the electrode extending through both layers to contact each layer on opposite sides. This vertical arrangement increases the breakdown voltage by utilizing the vertical electric field distribution, making the device suitable for high-current power applications.
3Reliability
If silicon semiconductor is used for power devices, then the device performance is adequate for conventional applications, but the breakdown voltage and current density reach theoretical limits
Solution Approach 1:
The invention changes the fundamental material parameter from silicon to group III-V nitride semiconductors. These materials possess inherently higher breakdown voltages and higher current density capabilities due to their wider bandgap and superior thermal properties. The electrode structure with dual conductive materials is specifically designed to exploit these material advantages, enabling the device to operate beyond the theoretical limits of silicon-based power devices.
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 allows for high breakdown voltage, high current density, and low on-resistance, effectively addressing the limitations of silicon semiconductor devices and enabling a high-performance power device with a normally-off operation.
Implementation Method 1
The first electrode portion is in contact (ohmic contact) with the P-type group III-V nitride semiconductor layer
Implementation Method 2
the second electrode portion is in contact (ohmic contact) with the N-type group III-V nitride semiconductor layer
Data Source
AI summary
The semiconductor device includes a P-type group III-V nitride semiconductor layer, an N-type group III-V nitride semiconductor layer, and an electrode in contact with both of the P-type group III-V nitride semiconductor layer and the N-type group III-V nitride semiconductor layer. The electrode includes a first electrode portion made of a first conductive material, and a second electrode portion, made of a second conductive material different from the first conductive material, bonded to the first electrode portion. The first electrode portion is in contact with the P-type group III-V nitride semiconductor layer, and the second electrode portion is in contact with the N-type group III-V nitride semiconductor layer.