K.S. Kaur

Shadowgraphic studies of triazene assisted laser-induced forward transfer of ceramic thin films

The laser-induced forward transfer process of solid ceramic donor materials (gadolinium gallium oxide and ytterbium doped yttrium aluminium oxide) was studied using triazene polymer as a sacrificial layer by means of a time-resolved nanosecond-shadowgraphy technique. The dependence of the ablation dynamics and quality of the ejected donor material on the laser fluence and thickness of the sacrificial and donor layers were investigated and discussed.

Triazene photopolymer dynamic release layer-assisted femtosecond laser-induced forward transfer with an active carrier substrate

Discs of solid material have been forward transferred from thin films on transparent carrier substrates using femtosecond Ti:sapphire laser-induced forward transfer (fs-LIFT) with a triazene polymer dynamic release layer (DRL). The fluence threshold for fs-LIFT was found to be only ≈20% of the DRL ablation threshold at the laser wavelength. This decrease is attributed to ultrafast shock-wave generation in the constrained polymer layer under femtosecond irradiation being the driving force for fs-LIFT with the polymer DRL. The result is very different from the nanosecond regime, where the LIFT threshold is observed to be slightly above the polymer ablation threshold. White-light continuum generation in a carrier substrate is observed and its influence on the fs-LIFT process is discussed.

Applications of laser printing for organic electronics

The development of organic electronic requires a non contact digital printing process. The European funded e-LIFT project investigated the possibility of using the Laser Induced Forward Transfer (LIFT) technique to address this field of applications. This process has been optimized for the deposition of functional organic and inorganic materials in liquid and solid phase, and a set of polymer dynamic release layer (DRL) has been developed to allow a safe transfer of a large range of thin films. Then, some specific applications related to the development of heterogeneous integration in organic electronics have been addressed. We demonstrated the ability of LIFT process to print thin film of organic semiconductor and to realize Organic Thin Film Transistors (OTFT) with mobilities as high as 4 10-2 cm2.V-1.s-1 and Ion/Ioff ratio of 2.8 105. Polymer Light Emitting Diodes (PLED) have been laser printed by transferring in a single step process a stack of thin films, leading to the fabrication of red, blue green PLEDs with luminance ranging from 145 cd.m-2 to 540 cd.m-2. Then, chemical sensors and biosensors have been fabricated by printing polymers and proteins on Surface Acoustic Wave (SAW) devices. The ability of LIFT to transfer several sensing elements on a same device with high resolution allows improving the selectivity of these sensors and biosensors. Gas sensors based on the deposition of semiconducting oxide (SnO2) and biosensors for the detection of herbicides relying on the printing of proteins have also been realized and their performances overcome those of commercial devices. At last, we successfully laser-printed thermoelectric materials and realized microgenerators for energy harvesting applications.

Influence of optical standing waves on the femtosecond laser-induced forward transfer of transparent thin films

The effects of the formation of an optical standing wave during femtosecond laser-induced forward transfer of transparent films is analyzed using a numerical interference model. The dependence of the intensity distribution on a number of easily controllable experimental parameters is investigated. Results of the model are compared to experimental studies of the transfer of gadolinium gallium oxide (GdGaO) with a polymer sacrificial layer. The model allows us to explain the observed variation in deposit morphology with the size of the air gap, and why forward transfer of the GdGaO was possible below the ablation thresholds of polymer and oxide.

Waveguide mode filters fabricated using laser-induced forward transfer

Titanium in-diffused lithium niobate index-tapered waveguides have been fabricated using laser-induced forward transfer technique for mode-filtering applications. Details of their fabrication, losses and transmission characterization are presented.

Printing of amorphous and crystalline materials pre-machined using focussed ion beam patterning

Laser Induced Forward Transfer (LIFT) is a laser-based direct write technique which has been routinely employed for trials of the deposition of organic and inorganic compounds, polymers and biomaterials on various substrates for the realisation of devices such as OLEDs [1]. This single-shot printing approach, which allows a spatially controlled pixel-by-pixel deposition has been widely trialled for printing as it enables operation in a standard ambient environment, has the ability to print a wide range of materials, allows printing of multilayered stacks composed of dissimilar materials, allows printing on both structured and planar substrates, and beam shaping of the incident laser pulse is also possible to further control the size and shape of the deposited material.