FLEXIBLE components in the GaN sector
FLEXIblue Gallium Nitride based devices
Financing : French National Research Agency (ANR) in partnership with the French Defence Procurement Agency (DGA)
Project partners :
Summary:
In recent years, we have seen the emergence of a new electronics sector based on conformable substrates. These include RFID tags, mobile sensors, flexible screens, etc. These electronics are essentially based on active organic materials, whose low mobility considerably limits the potential applications of flexible electronics in the radio-frequency field.
In this context, the aim of the FLEXIGaN project is to develop new approaches leading to several conformable (flexible, stretchable) electronics technologies to meet the power, efficiency and high-frequency requirements of these new applications. Gallium nitride is a promising material for achieving these performances. The aim of the FLEXIGaN project is to obtain flexible GaN transistors (HEMTs) delivering 2W/mm at X-band and flexible GaN LEDs with an external quantum efficiency of 5%.
FLEXIGaN is a forward-looking programme in which the convergence between epitaxy, the flexible substrate and the manufacturing process is achieved in a concerted and integrated manner.
The originality of the FLEXIGaN project is based on innovations consisting in obtaining an epitaxy resistant to mechanical stress and a flexible support adapted to power applications in line with a specific technological manufacturing process.
Three technological strategies will be investigated in order to achieve the objectives of increasing frequency on flexible media.
The first strategy is based on the heterogeneous integration of GaN HEMTs and LEDs fabricated on rigid substrates and transferred to flexible supports.
The second strategy is similar to the first, but a laser cutting step is added before transfer to obtain individual cells on the flexible substrate so as to limit stresses in the epitaxy when the flexible is deformed.
The third strategy concerns flexible LEDs only. The process begins with the manufacturing stages on a rigid substrate (on the n side then on the p side after an initial epitaxy transfer stage) and ends with transfer to a flexible substrate.
Once the results of the first devices allow it, reliability tests will be carried out to determine the endurance of the flexible components to repeated deformation and high temperatures.
Abstract:
At the present time, the large majority of electronic devices is fabricated on rigid substrates but, in recent years, electronic devices and circuits on flexible substrates have attracted a great deal of attention and open new opportunities for a wide range of applications such as flexible radio-frequency identification tags (RFID), mobile sensors, flexible displays,... For these applications, flexible organic or inorganic devices are commonly developed. But, frequency performance as well as light emitted power of organic devices is strongly limited by the poor mobility of organic semiconductors and by the resolution of printing techniques. Our strategy to obtain flexible devices is based on high speed/high power/high performance principles. Many emerging applications require high frequency performance. In our case, the target applications such as logistic tracking-preventive maintenance-objects traceability need also power and high efficiency performance. These parameters are out of reach for the existing
In this context, the activity proposed in FLEXIGaN project is a new approach in order to develop several technological options to obtain flexible electronics (bendable, stretchable), meeting the power, efficiency and high frequency of new applications. Gallium nitride is a promising material to achieve this performance. The objective of FLEXIGaN consortium is to obtain on the one hand flexible GaN-based HEMTs (High Electron Mobility Transistors) delivering 2W/mm up to X band and on the other hand GaN-based flexible LEDs (Light Emitting Diodes) with an external quantum efficiency of 5%.
FLEXIGaN project is a prospective project in which is realized in a real integrated and concerted way the convergence between the epilayer, the flexible tape and the technological process. The originality of FLEXIGaN project concerns innovation based on the nature of epitaxy withstanding the mechanical stress and the flexible tape characteristics dedicated for power applications in adequacy with adjusted processing steps.
In order to achieve the objectives of increasing frequency on flexible support, three technological strategies will be investigated.
The first strategy targets the heterogeneous integration and assembly of state-of-the-art GaN/Silicon based devices (HEMTs and LEDs) onto a flexible tape.
The second strategy is similar to the first one but a step of laser patterning is added before the transfer process in order to obtain individual cell on flexible tape and so limit stress in epimaterial during the bending.
The third strategy concerns only flexible LEDs. The process starts with the fabrication steps on rigid substrate (on n-face and then on p-face after a first layer transfer) and follows with transfer on flexible tape.
When the results of the first devices permit to do it, reliability tests will be achieved to know the endurance of flexible components to repetitive deformation and high temperature.