Flexible GaN HEMT on Thinned SiC for Heat-Stable Microwave Power
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for preparing flexible GaN HEMTs suffer from severe lattice mismatch between Si substrates and GaN, leading to poor device performance and damage during the transfer process, along with inadequate heat dissipation due to air bubbles and gaps at the contact interface.
Innovation Solution
A flexible microwave power transistor is developed using a rigid SiC substrate with a GaN HEMT layer, where the SiC substrate is thinned and a flexible Parylene-C substrate is grown at room temperature, reducing lattice mismatch and retaining part of the SiC for improved heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Si substrate is used to prepare GaN HEMT, then the device can be fabricated, but severe lattice mismatch occurs leading to poor device performance
Solution Approach 1:
The patent introduces an AlN nucleation layer as an intermediary between the Si substrate and the GaN channel layer. This intermediate layer serves as a buffer to reduce the severe lattice mismatch between Si and GaN, thereby improving device performance while enabling fabrication on Si substrates.
2Adaptability or versatility
If the Si substrate is completely removed and the device is transferred to a flexible substrate, then flexibility is achieved, but the device is easily deformed and damaged during transfer
Solution Approach 1:
The patent performs preliminary thinning of the Si substrate to a thickness of 5 μm or less before the transfer process. This preliminary action makes the substrate more flexible and easier to transfer while reducing the risk of device deformation and damage during the transfer process.
3Adaptability or versatility
If the device is transferred using a traditional method, then the device can be moved to a flexible substrate, but air bubbles and gaps form at the contact interface reducing heat dissipation performance
Solution Approach 1:
The patent performs preliminary thinning of the Si substrate to 5 μm or less before transfer. This thinning enables the substrate to conform better to the flexible substrate surface, reducing the formation of air bubbles and gaps at the contact interface, thereby improving heat dissipation performance.
4Adaptability or versatility
If the Si substrate is thinned to reduce flexibility issues, then transfer becomes easier, but the substrate becomes too weak and prone to damage
Solution Approach 1:
The patent applies partial thinning of the Si substrate to a specific thickness of 5 μm or less, which is sufficient to achieve flexibility and ease of transfer, while retaining enough material to maintain adequate substrate strength and resistance to damage during the transfer process.
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 approach significantly enhances power output capability, efficiency, and gain while minimizing device damage and maintaining performance under stress, with improved heat dissipation and reduced air bubbles and gaps.
Implementation Method 1
growing a flexible Parylene-C substrate on a lower surface of the rigid SiC substrate of the thinned rigid microwave power transistor at room temperature
Data Source
AI summary
The present disclosure provides a flexible microwave power transistor and a preparation method thereof. In view of great lattice mismatch and poor performance of a device prepared with a Si substrate in an existing preparation method, the preparation method of the present disclosure grows a gallium nitride high electron mobility transistor (GaN HEMT) layer on a rigid silicon carbide (SiC) substrate to avoid lattice mismatch between a silicon (Si) substrate and gallium nitride (GaN), improving performance of the flexible microwave power transistor. Moreover, in view of problems such as low output power, power added efficiency and power gain with the existing device preparation method, the present disclosure retains part of the rigid SiC substrate and grows a flexible substrates at room temperature to prepare a high-quality device. The present disclosure has greatly improved power output capability, efficiency and gain, and basically unchanged performance of device under 0.75% of stress.