Periodic Reporting for period 2 - CoolHEMT (Next Generation GaN Power Amplifiers)
Période du rapport: 2019-09-01 au 2021-02-28
The CoolHEMT project is designed to commercialize SweGaN’s unique gallium nitride (GaN) on silicon carbide (SiC) structure for high frequency devices. SweGaN’s technology to grow GaN on SiC enables an extremely thin structure, called QuanFINE, to be grown. It gives several advantages, such as higher power density, lower dispersion, and better thermal management. These advantages are critical for a robust and high performance communication network. For end users, we enable higher performance and lower power consumption. For telecom, this means faster data transfer, while saving the environment. In the project, high electron mobility transistor (HEMT) devices have been developed and tested together with customers. During the project, SweGaN has:
• Optimized the epitaxial stack and benchmarked devices made on QuanFINE against the best commercial material on the market today. The QuanFINE based devices have 50 % lower dispersion than devices made on commercial material.
• A production tool has been designed, installed, and tuned in, and material from this tool is being qualified with customers.
• Devices have been sent to customers for evaluation and feedback has been received for further optimization of the processing and the epitaxial stack.
• Transistor modelling has commenced and MMIC designs and simulations have been performed.
• We have presented at several conferences and workshops.
• We have hired two industrial PhD students.
• Patent applications have been filed and a trademark has been registered.
• Sales have increased both within and outside of Europe. Particularly Italy, Japan, and Taiwan are showing great interest in SweGaN’s material.
• We have also started to look at the power market, due to the outstanding ability of the QuanFINE material to handle high electric fields.
Within this project, objectives have been to explore, develop, and commercialize the QuanFINE structure. It can reduce power consumption in base stations while providing greater bandwidth. The overall objectives have been to optimize the QuanFINE material, develop the market and sell the material, develop HEMT devices, and generate transistor models and MMIC designs that can be tested by end-users. The QuanFINE structure has been optimized within this project, allowing us to grow our unique thin structure with well controlled uniformity on both 4” and 6” substrates. We have successfully fabricated HEMTs on QuanFINE wafers, however, MMIC fabrication has been delayed due to equipment malfunction. Within this project, we have managed to expand our base of customers to reach over 70 % of the RF market through them. We are also talking to customers in the power market, as QuanFINE can handle both high switching frequencies and high power densities. We have set up a new facility for developing SiC substrates during this project, which aims to give us a more stable supply of high quality substrates at a competitive cost.
• Optimized the epitaxial stack and benchmarked devices made on QuanFINE against the best commercial material on the market today. The QuanFINE based devices have 50 % lower dispersion than devices made on commercial material.
• A production tool has been designed, installed, and tuned in, and material from this tool is being qualified with customers.
• Devices have been sent to customers for evaluation and feedback has been received for further optimization of the processing and the epitaxial stack.
• Transistor modelling has commenced and MMIC designs and simulations have been performed.
• We have presented at several conferences and workshops.
• We have hired two industrial PhD students.
• Patent applications have been filed and a trademark has been registered.
• Sales have increased both within and outside of Europe. Particularly Italy, Japan, and Taiwan are showing great interest in SweGaN’s material.
• We have also started to look at the power market, due to the outstanding ability of the QuanFINE material to handle high electric fields.
Within this project, objectives have been to explore, develop, and commercialize the QuanFINE structure. It can reduce power consumption in base stations while providing greater bandwidth. The overall objectives have been to optimize the QuanFINE material, develop the market and sell the material, develop HEMT devices, and generate transistor models and MMIC designs that can be tested by end-users. The QuanFINE structure has been optimized within this project, allowing us to grow our unique thin structure with well controlled uniformity on both 4” and 6” substrates. We have successfully fabricated HEMTs on QuanFINE wafers, however, MMIC fabrication has been delayed due to equipment malfunction. Within this project, we have managed to expand our base of customers to reach over 70 % of the RF market through them. We are also talking to customers in the power market, as QuanFINE can handle both high switching frequencies and high power densities. We have set up a new facility for developing SiC substrates during this project, which aims to give us a more stable supply of high quality substrates at a competitive cost.
We have been focused on improving the performance of the QuanFINE material, set up a pilot production line for growing epi-wafers, processing HEMT devices, and commercializing the material. Several improvements have been developed on the epitaxial stack, resulting in a large reduction in dispersion. We have installed and tuned in a new production tool, which has significantly increased our throughput and control of quality, uniformity, and reproducibility. Previously, semi-insulating (SI) silicon carbide (SiC) substrates of high quality could be obtained in Europe. Now we need to purchase from USA and China. Neither the quality control nor the price of these substrates have been satisfactory, which led us to start developing our own substrates, which has been amended to the project. We have set up a new facility for the development of in-house SI SiC substrates. We have also prepared for and simulated MMIC designs for the fabrication of transistor devices on QuanFINE. We have discovered that the QuanFINE material defied previous assumptions, and despite being only a few 100 nm thick, could block extremely high voltages, which led to a slight adjustment of our focus within the project. The commercialization has gone well in terms of creating interest around our material. We have more customers, most being repeat customers. Most interesting is the Asian market, especially Japan. During the first year, some deliveries to Taiwan were delayed due to waiting for export licenses, but we now have good communication with the Swedish Inspectorate of Strategic Products (ISP) and can swiftly export our material. Fiscal year 2019 was a record year for SweGaN in terms of sales. During fiscal year 2020, we continued to increase the interest in our material, and also received and delivered on our first pilot-production order. This was an order that came from one of our European customers, giving us both a boost in sales and strengthened our position within the European supply chain. The success in 2020 led to a new sales record, and now in 2021 we are continuing on the same track. The boost in development and sales for SweGaN has been made possible by this project.
The QuanFINE material outperforms the best material in the world. However, work is ongoing to improve the performance further. Parallel processing with the best commercial material today shows that QuanFINE gives 10 % higher power density, estimated 30 % lower thermal resistance, and 10 % lower knee walkout. Furthermore, the improved version of QuanFINE gives as much as 50 % lower knee walkout. The dispersion is something we look carefully at and a third version is being developed with even better performance. The impact this has is that more efficient base stations can be built and thanks to the high thermal dissipation, it will be easier to realize massive MIMO, which is an essential technology for an energy efficient 5G network; a major challenge to realize massive MIMO is the cooling. The high efficiency and low dispersion will also reduce the energy consumption in the base stations. After deeper testing, it has become evident that QuanFINE has a very high voltage blocking capability. There is a lot of hype around GaN power devices and enormous amounts of money is pumped into researching GaN on Si which is proving to be very unreliable and hard to push beyond 600 V. The higher the voltage, the thicker the layer needs to be, which is creating huge difficulties for GaN-on-Si. QuanFINE, by contrast, which is extremely thin, was expected to not be able to block high voltages, but when tested, it blocked 1.5 kV. This measurement has been repeated several times by different groups and blocking voltages in excess of 2 kV have been demonstrated. More impressive is the peak electric field. The higher this field can be, the closer the contacts can be placed on the HEMT structure and the lower the on resistance and the higher the frequency can be. The maximum field measured so far is close to 2 MV/cm. The best GaN on Si only reaches around 0.7 MV/cm. With a contact spacing of only 5 µm, the QuanFINE can block close to 1 kV. This leads to one order of magnitude lower on resistance compared to GaN on Si or SiC on SiC power devices. This means that an electric vehicle can get around 20 % longer range, and charging the battery is faster. The substantially higher switching frequency can greatly increase the power density of the system, making laptop and phone chargers much smaller and more efficient than today.