FLEXIble Gallium Nitride based devices – FLEXIGAN

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 ,…
In this context, the activity proposed in FLEXIGaN project is to bring breakthrough in the flexible electronic domain. Gallium nitride is a promising material to achieve these performances. 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 InGaN/GaN-based flexible LEDs (Light Emitting Diodes) with an external quantum efficiency of 5%.

On the one hand, the aim is to produce Autonomous Power RF Tags for the HEMTs technology. The consortium intends to produce high speed/high power/high performance flexible devices. This strategy to achieve these flexible TAGs is well suited versus organic electronics (suffering of low mobility) and graphene electronics and circuits (limited by low bias). Lot of emerging applications requires high frequency performance. In our case, the target applications such as logistic tracking-preventive maintenance-objects traceability need also power and high efficiency performance.

In the second hand, it aims the fabrication bendable InGaN/GaN LEDs leading to create flexible light source with a volume emission compared with OLEDs which provide surface brightness. In our case, the aim is to fabricate flexible blue LEDs more robust regarding the moisture (no encapsulation barrier is needed for LEDs comparing to OLEDs) and not strongly sensitive to the temperature.

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 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.