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GreenDiamond Report Summary

Project ID: 640947
Funded under: H2020-EU.3.3.5.

Periodic Reporting for period 1 - GreenDiamond (Green Electronics with Diamond Power Devices)

Reporting period: 2015-05-01 to 2016-04-30

Summary of the context and overall objectives of the project

14 European research centers and firms coming from 6 European countries will during 4 years - May 2015 to April 2019 - develop diamond based power electronics devices. 3 to 30 times better than the actual used materials, diamond will enable to diminish loses, thermal requirements and the weight, through the higher blocking voltages, of the current devices and to enhance at the same time the overall reliability and performances.

For competitive low-carbon renewable energy and smart grid applications, the impact of power electronics is striking. Approximately 30% of all electric power generated utilises Power Electronics somewhere between the point of generation and its end use. Power electronics is used for more efficient renewable energy production and distribution including in highly-efficient electricity distribution over long distances via High Voltage Direct Current power lines (HVDC) as well as in the better control of loads in switching power supplies and variable-speed drives for motors that drive fans, pumps, and compressors. By 2030, it is expected that perhaps as much as 80% of all electric power will use power electronics somewhere between generation and consumption. Even with state-of-the-art electric equipment, the transformation of the electrical energy occurs with significant losses (for example 9% in Spain from the source to the point of use), because available semiconductors aren’t ideal for high power. In future smart grids involving delocalised renewable energy sources, these energy losses become even more important, since power electronics are needed throughout the grid to monitor and control the ever-changing supply and demand of low-carbon electricity transiting through the grid. This is even more critical in the case of offshore wind farms where an efficient energy transportation technology, such as HVDC, is required.
The key to the efficient transmission and conversion of low-carbon electrical energy is the improvement of power electronic devices, which must be durable and reliable in high power high power environments to eliminate the need for auxiliary systems. “Green electronics”, i.e. highly efficient electronic devices are crucially important for our future energy system as they will increase the efficiency of electricity production and distribution with very disruptive gains expected at the system level. First estimation gives a factor of 4 improvement, ie 75% reduction in losses, representing about 10 MW energy saving on a 300 MW HVDC converter. They will also provide more flexibility, facilitating the introduction of variable and distributed sources of renewable energies into the grid. In this context, the GreenDiamond project will contribute knowledge, new approaches, innovative materials and skills arising from the cross-fertilisation with materials and electronics research in order yielding more efficient and cost-competitive energy technologies.
Silicon is a well-established starting material that has addressed the requirements of energy conversion for more than 50 years. However, it is widely recognised (as shown in research roadmaps on power semiconductor devices) that a real step-improvement in Power Electronics will be obtained by employing devices based on wide bandgap semiconductor materials. Wide bandgap semiconductor materials have superior electrical characteristics for power devices when compared to silicon. Power electronic devices based on wide bandgap semiconductor materials will result in substantial improvements in the performance of power electronics systems by offering higher blocking voltages, improved efficiency and reliability, as well as reduced thermal requirements thus leading to realisation of more efficient green electronic systems. Among wide bandgap semiconductors, diamond is considered to be the ultimate semiconductor for applications in high power electronics due to its exceptional properties. Its dielectric breakdown strength is 3 times higher than in SiC and more than 30 times better than in Si. In addition, the carrier mobility is very high for both carrier types and the thermal conductivity is unsurpassed.

The objectives of the GreenDiamond project are therefore to fabricate the first high power electronic device in diamond that is competitive with existing wide-band-gap semiconductor technologies, and realise the first power converter using these diamond devices, opening new commercial and industrial opportunities. The GreenDiamond prototypes at 6.5kV and 10kV operating voltages based on Diamond MOSFETs will address the key requirements for low carbon energy power electronics applications:
- Lower power losses and more energy efficient operation in high voltage applications
- Novel more efficient power converter topologies (integrated switching cell)
- Enhanced thermal properties (lower losses at higher temperature) which will result in simplified thermal management and improved reliability in harsh operating environments
- Higher current density than Si, SiC or GaN transistors
- Higher voltage capability than Si, SiC or GaN transistors
- Compatibility with Si processes
- Improved reliability in harsh operating environment..

In order to achieve these goals, the consortium will design and optimize state of the art technology for the fabrication of 6.5 kV and 10 kV devices with specific ON state resistances varying between 20 mOhm.cm2 and 100 mOhm.cm2. In parallel to the diamond-based chip development, a significant effort will be invested in the design of new packaging suitable for high voltage devices working up to 250°C.
The devices proposed will enable the fabrication of power converters with higher efficiency; reduced weight and size; and with easier control and thermal management, all these factors leading to lower maintenance and improved reliability. In addition this project paves the way towards the fabrication of devices working at even higher voltages, 20 kV or more, limited only by design and packaging, as the intrinsic limitation of diamond permits yet higher voltages.

GreenDiamond will thus accelerate the development of transformative energy technologies from TRL2 to TRL4 with no environmental, resource efficiency and safety issues (see Figure attached)

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

1. To develop simulation models and parameters suitable for analysis of diamond devices’ analysis.
This first objective has been achieved by WP2. The simulation will be continuously refined taking into account electrical resultas obtained n the devices fabricated within the consortium.

2. To fabricate Prototype MOS transistors in several stages 
The process is on-going for the fabrication of the first Diamond MOS transistor. The process involves 7 main tasks carried out by at least 4 partners, ie substrate procurement/characterization (IAF-ESRF), p+/p- epitaxy (CNRS/NEEL-CEA), n epitaxy (IMEC-IAF), p+ epitaxy (CNRS/NEEL), etching (UCL-IAF), Oxyde deposition (NEEL-CNM), metallization (CNRS-CNM). Each step is being studied separately, and 4 samples are already in the process flow for the full transistor fabrication. These first samples are currently in the p+/p-/n state, and are waiting for the second p+ epilayer. For these first transistors the design has not been optimized, so electrical performances will be lower than the final target.

3. To design and develop high quality, cost-effective package solutions suitable for the robust operation of 6.5 kV and 10 kV rated devices under extreme conditions
This task is on-going. The package type has already been identified (SOT-227), some base plate, die-attach and topside interconnections have been tested and further exploration is on-going.

4. To develop reliability tests for normal and extreme operating conditions of the developed power devices 
The measurement probe stations and equipment are ready to measure any preliminary device or diamond transistor prototype. A first power commutation cell has been realized, with diamond Schottky diode, to test the equipment.

5. To demonstrate a high voltage three-phase DC/AC high-power converter based on diamond devices 
A 30kV – 2W hybrid gate driver has been designed and a first prototype has been realized. Three possible topologies have been considered to deploy a HVDC or MV application.

6. To disseminate the outcomes within EU and provide the foundation for industrialisation
Results have already been presented in scientific conferences. 

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

GreenDiamond will advance the TRL of energy technologies that will form the backbone of the energy system by 2030:

GreenDiamond will accelerate the development from TRL2 to TRL4 of promising technologies for Power Electronics with no negative environmental, resource or safety issues. The vision of the consortium is to enable
highly integrated, cost competitive and reliable diamond power electronics devices and components to improve functionality, reliability, and efficiency of next-generation, low-carbon components and systems. A successful outcome will respond perfectly to the expected impacts of the LCE-01-2014 call.
We must start developing Power Electronics of the future now. By 2030, 80% of all electric power will flow through Power Electronics at some point between generation and distribution (currently 30%).

New contributions to the energy challenge in Europe and worldwide:

Wide bandgap (WBG) semiconductor materials, especially diamond, allow power electronic components to be orders of magnitude more efficient, smaller, faster and more reliable than their silicon (Si)-based counterparts. These enabling technologies make it possible to reduce energy losses, weight, volume, and life-cycle costs in a wide range of power applications. And as Europe transitions toward a digital and low-carbon economy, there is a clear need to modernise the aging electric grid and add functionalities.
Meanwhile, worldwide electricity consumption is expected to increase 56% between 2010 and 2040. This leads to a correspondingly rapid growth in demand for Power Electronics beyond Europe. The global market for low-carbon goods and services was worth 4 trillion euros in 2008 and is projected to
grow by 50% to just under 6 trillion euros by 2015, the majority enabled by Power Electronics. Specifically, the power electronics market was estimated at 15 billion € in 2012 and should reach 28 billion € in 2020. The specific target of GreenDiamond is the high voltage applications, i.e. devices operating above 1.7kV, with a total addressable market estimated to about 1.5 billion €.

More efficient, low-carbon electricity production and distribution:

Worldwide, fossil fuels continue to supply over 60% of world electricity. Therefore, the significant gains in efficiency in electricity production and distribution thanks to the use of wide-band gap diamond in Power Electronics will lead to overall reductions in fossil fuels used and carbon emissions worldwide.
Wide band gap Power Electronics, like those enabled by GreenDiamond’s expected results, will allow
engineers and researchers to solve many core energy efficiency challenges, as modulate current flow and enable precise control of the electric grid. GreenDiamond Wide Band Gap (WBG) materials will also have the potential to reduce transformer size by a factor of ten or more.

Power Electronics will contribute to the low-carbon society via energy efficiency:

Power Electronics has the potential to make a huge contribution to the low carbon economy. For example, power savings on conventional electrical devices of 30 to 40% have already been realised in specific cases, and this is only the begining. Power Electronics eliminates up to 90% of the power losses that currently occur during ACto-DC and DC-to-AC electricity conversion.
The better the power electronics, the greater the contribution is. Since diamond has by far the best material properties, it would therefore have the greatest impact. The GreenDiamond consortium includes the world-recognised leaders anywhere in Europe in diamond research and technology.

Diamond is Gaia’s best friend:

In the future (30 years) all high voltage applications should benefit from the higher efficiency, durability and reliability of diamond devices, reducing significantly electrical losses, overall system complexity, and improving reliability. The GreenDiamond technology is inherently safe, Diamond is not on the REACH List it is non-toxic and its precursor (carbon) is abundant and can be made from renewable sources.
The key difficulty today in manufacturing diamond devices is the commercial lack of diamond substrate in large wafer sizes. GreenDiamond will demonstrate the feasibility of diamond devices for Power Electronics, thereby creating the market and opening the way for synthetic diamond wafers to become commercially competitive with silicon, as well as develop the supply chain.

Impacts of the focus on High Voltage Direct current Converters (HVDC):

Current technology has an efficiency of 96% (for Self-Commutated Voltage-Sourced Converters (SC/VSC)). According to a recent study based on Si IGBT devices, is reasonable to think that the future diamond MOSFET power converters would lead to an efficiency of around 99%, reducing losses by 75%. The use of GreenDiamond higher voltage devices would significantly reduce the quantity of the auxiliaries, leading to reduced losses, cost and physical space as well improved reliability. For offshore applications, the reduction of space (and weight) requirement will enable a much lower cost overall and, therefore, an attractive system solution.

The following impacts are thus expected from the successful completion of the GreenDiamond project:
- Increasing the reliability and operating lifespan of components
- Considerable improvement of power-electronic devices’ performance
- Reducing initial and maintenance costs
- Improving efficiency

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