Substrate nanopatterning by e-beam lithography to growth ordered arrays of III-nitride nanodetectors, white light emitters, and solar cells

III-nitride nanorods have attracted much scientific interest during the last decade because of their unique optical and electrical properties [1,2]. The high crystal quality and the absence of extended defects make them ideal candidates for the fabrication of high efficiency opto-electronic devices such as nano-photodetectors, light-emitting diodes, and solar cells [1-3]. Nitride nanorods are commonly grown in the self-assembled mode by plasma-assisted molecular beam epitaxy (MBE) [4]. However, self-assembled nanorods are characterized by inhomogeneous heights and diameters, which render the device processing very difficult and negatively affect the electronic transport properties of the final device. For this reason, the selective area growth (SAG) mode has been proposed, where the nanorods preferentially grow with high order on pre-defined sites on a pre-patterned substrate

Microfabrication processes for microfluidic devices on a single laser Workstation: direct writing lithography on SU-8, laser ablation on polymers and mask manufacturing

We demonstrate the capability of a laser micromachining workstation for cost-effective manufacturing of a variety of microfluidic devices, including SU-8 microchannels on silicon wafers and 3D complex structures made on polyimide Kapton® or poly carbonate (PC). The workstation combines a KrF excimer laser at 248 nm and a Nd3+:YVO4 DPSS with a frequency tripled at 355 nm with a lens magnification 10X, both lasers working at a pulsed regime with nanoseconds (ns) pulse duration. Workstation also includes a high-resolution motorized XYZ-tilt axis (~ 1 um / axis) and a Through The Lens (TTL) imaging system for a high accurate positioning over a 120 x 120 mm working area. We have surveyed different fabrication techniques: direct writing lithography,mask manufacturing for contact lithography and polymer laser ablation for complex 3D devices, achieving width channels down to 13μ m on 50μ m SU-8 thickness using direct writing lithography, and width channels of 40 μm for polyimide on SiO2 plate. Finally, we have tested the use of some devices for capillary chips measuring the flow speed for liquids with different viscosities. As a result, we have characterized the presence of liquid in the channel by interferometric microscopy.

Critical aspects of substrate nanopatterning for the ordered growth of GaN nanocolumns.

Precise and reproducible surface nanopatterning is the key for a successful ordered growth of GaN nanocolumns. In this work, we point out the main technological issues related to the patterning process, mainly surface roughness and cleaning, and mask adhesion to the substrate. We found that each of these factors, process-related, has a dramatic impact on the subsequent selective growth of the columns inside the patterned holes. We compare the performance of e-beam lithography, colloidal lithography, and focused ion beam in the fabrication of hole-patterned masks for ordered columnar growth. These results are applicable to the ordered growth of nanocolumns of different materials.

Selective area growth of a- and c-plane GaN nanocolumns by molecular beam epitaxy using colloidal nanolithography

Selective area growth of a-plane GaN nanocolumns by molecular beam epitaxy was performed for the first time on a-plane GaN templates. Ti masks with 150 nm diameter nanoholes were fabricated by colloidal lithography, an easy, fast and cheap process capable to handle large areas. Even though colloidal lithography does not provide a perfect geometrical arrangement like e-beam lithography, it produces a very homogeneous mask in terms of nanohole diameter and density, and is used here for the first time for the selective area growth of GaN. Selective area growth of a-plane GaN nanocolumns is compared, in terms of anisotropic lateral and vertical growth rates, with GaN nanocolumns grown selectively on the c-plane

Fabrication of sub-100 nm IDT SAW devices on insulating, semiconducting and conductive substrates

This work describes the electron-beam (e-beam) lithography process developed to manufacture nano interdigital transducers (IDTs) to be used in high frequency (GHz) surface acoustic wave (SAW) applications. The combination of electron-beam (e-beam) lithography and lift-off process is shown to be effective in fabricating well-defined IDT finger patterns with a line width below 100 nm with a good yield. Working with insulating piezoelectric substrates brings about e-beam deflection. It is also shown how a very thin organic anti-static layer works well in avoiding this charge accumulation during e-beam lithography on the resist layer. However, the use of this anti-static layer is not required with the insulating piezoelectric layer laying on a semiconducting substrate such as highly doped silicon. The effect of the e-beam dose on a number of different layers (of insulating, insulating on semiconducting, semiconducting, and conductive natures) is provided. Among other advantages, the use of reduced e-beam doses increases the manufacturing time. The principal aim of this work is to explain the interrelation among e-beam dose, substrate nature and IDT structure. An extensive study of the e-beam lithography of long IDT-fingers is provided, in a wide variety of electrode widths, electrode numbers and electrode pitches. It is worthy to highlight that this work shows the influence of the e-beam dose on five substrates of different conductive nature

Fabrication of GaN nanorods by focused ion beam

Ordered arrays of III-Nitride nanocolumns are excellent candidates for the fabrication of nano-optoelectronic devices. Different technologies such as e-beam lithography or colloidal lithography, have been used to obtain ordered arrays. All these technologies have in common several processing steps that can affect the crystalline growth of the nanocolumns. In this work, we present a single lithographic step that permits to grow ordered GaN nanocolumns with different geometries. The patterning is based in the use of a focusedionbeam with different doses. With this method has been possible to create GaN nanopillars and nanocylinders

Crecimiento, fabricación y caracterización de heteroestructuras y nanocolumnas ordenadas basadas en nitruros del grupo III para aplicaciones sensoras

Esta memoria está basada en el crecimiento y caracterización de heteroestructuras Al(Ga)N/GaN y nanocolumnas ordenadas de GaN, y su aplicación en sensores químicos. El método de crecimiento ha sido la epitaxia de haces moleculares asistida por plasma (PAMBE). En el caso de las heteroestructuras Al(Ga)N/GaN, se han crecido barreras de distinto espesor y composición, desde AlN de 5 nm, hasta AlGaN de 35 nm. Además de una caracterización morfológica, estructural y eléctrica básica de las capas, también se han fabricado a partir de ellas dispositivos tipo HEMTs. La caracterización eléctrica de dichos dispositivos (carga y movilidad de en el canal bidimensional) indica que las mejores heteroestructuras son aquellas con un espesor de barrera intermedio (alrededor de 20 nm). Sin embargo, un objetivo importante de esta Tesis ha sido verificar las ventajas que podían tener los sensores basados en heteroestructuras AlN/GaN (frente a los típicos basados en AlGaN/GaN), con espesores de barrera muy finos (alrededor de 5 nm), ya que el canal de conducción que se modula por efecto de cambios químicos está más cerca de la superficie en donde ocurren dichos cambios químicos. De esta manera, se han utilizado los dispositivos tipo HEMTs como sensores químicos de pH (ISFETs), y se ha comprobado la mayor sensibilidad (variación de corriente frente a cambios de pH, Ids/pH) en los sensores basados en AlN/GaN frente a los basados en AlGaN/GaN. La mayor sensibilidad es incluso más patente en aplicaciones en las que no se utiliza un electrodo de referencia. Se han fabricado y caracterizado dispositivos ISFET similares utilizando capas compactas de InN. Estos sensores presentan peor estabilidad que los basados en Al(Ga)N/GaN, aunque la sensibilidad superficial al pH era la misma (Vgs/pH), y su sensibilidad en terminos de corriente de canal (Ids/pH) arroja valores intermedios entre los ISFET basados en AlN/GaN y los valores de los basados en AlGaN/GaN. Para continuar con la comparación entre dispositivos basados en Al(Ga)N/GaN, se fabricaron ISFETs con el área sensible más pequeña (35 x 35 m2), de tamaño similar a los dispositivos destinados a las medidas de actividad celular. Sometiendo los dispositivos a pulsos de voltaje en su área sensible, la respuesta de los dispositivos de AlN presentaron menor ruido que los basados en AlGaN. El ruido en la corriente para dispositivos de AlN, donde el encapsulado no ha sido optimizado, fue tan bajo como 8.9 nA (valor rms), y el ruido equivalente en el potencial superficial 38.7 V. Estos valores son más bajos que los encontrados en los dispositivos típicos para la detección de actividad celular (basados en Si), y del orden de los mejores resultados encontrados en la literatura sobre AlGaN/GaN. Desde el punto de vista de la caracterización electro-química de las superficies de GaN e InN, se ha determinado su punto isoeléctrico. Dicho valor no había sido reportado en la literatura hasta el momento. El valor, determinado por medidas de “streaming potential”, es de 4.4 y 4 respectivamente. Este valor es una importante característica a tener en cuenta en sensores, en inmovilización electrostática o en la litografía coloidal. Esta última técnica se discute en esta memoria, y se aplica en el último bloque de investigación de esta Tesis (i.e. crecimiento ordenado). El último apartado de resultados experimentales de esta Tesis analiza el crecimiento selectivo de nanocolumnas ordenadas de GaN por MBE, utilizando mascaras de Ti con nanoagujeros. Se ha estudiado como los distintos parámetros de crecimiento (i.e. flujos de los elementos Ga y N, temperatura de crecimiento y diseño de la máscara) afectan a la selectividad y a la morfología de las nanocolumnas. Se ha conseguido con éxito el crecimiento selectivo sobre pseudosustratos de GaN con distinta orientación cristalina o polaridad; templates de GaN(0001)/zafiro, GaN(0001)/AlN/Si, GaN(000-1)/Si y GaN(11-20)/zafiro. Se ha verificado experimentalmente la alta calidad cristalina de las nanocolumnas ordenadas, y su mayor estabilidad térmica comparada con las capas compactas del mismo material. Las nanocolumnas ordenadas de nitruros del grupo III tienen una clara aplicación en el campo de la optoelectrónica, principalmente para nanoemisores de luz blanca. Sin embargo, en esta Tesis se proponen como alternativa a la utilización de capas compactas o nanocolumnas auto-ensambladas en sensores. Las nanocolumnas auto-ensambladas de GaN, debido a su alta razón superficie/volumen, son muy prometedoras en el campo de los sensores, pero su amplia dispersión en dimensiones (altura y diámetro) supone un problema para el procesado y funcionamiento de dispositivos reales. En ese aspecto, las nanocolumnas ordenadas son más robustas y homogéneas, manteniendo una alta relación superficie/volumen. Como primer experimento en el ámbito de los sensores, se ha estudiado como se ve afectada la emisión de fotoluminiscencia de las NCs ordenadas al estar expuestas al aire o al vacio. Se observa una fuerte caída en la intensidad de la fotoluminiscencia cuando las nanocolumnas están expuestas al aire (probablemente por la foto-adsorción de oxigeno en la superficie), como ya había sido documentado anteriormente en nanocolumnas auto-ensambladas. Este experimento abre el camino para futuros sensores basados en nanocolumnas ordenadas. Abstract This manuscript deals with the growth and characterization of Al(Ga)N/GaN heterostructures and GaN ordered nanocolumns, and their application in chemical sensors. The growth technique has been the plasma-assisted molecular beam epitaxy (PAMBE). In the case of Al(Ga)N/GaN heterostructures, barriers of different thickness and composition, from AlN (5 nm) to AlGaN (35 nm) have been grown. Besides the basic morphological, structural and electrical characterization of the layers, HEMT devices have been fabricated based on these layers. The best electrical characteristics (larger carriers concentration and mobility in the two dimensional electron gas) are those in AlGaN/GaN heterostructures with a medium thickness (around 20 nm). However, one of the goals of this Thesis has been to verify the advantages that sensors based on AlN/GaN (thickness around 7 nm) have compared to standard AlGaN/GaN, because the conduction channel to be modulated by chemical changes is closer to the sensitive area. In this way, HEMT devices have been used as chemical pH sensors (ISFETs), and the higher sensitivity (conductance change related to pH changes, Ids/pH) of AlN/GaN based sensors has been proved. The higher sensibility is even more obvious in application without reference electrode. Similar ISFETs devices have been fabricated based on InN compact layers. These devices show a poor stability, but its surface sensitivity to pH (Vgs/pH) and its sensibility (Ids/pH) yield values between the corresponding ones of AlN/GaN and AlGaN/GaN heterostructures. In order to a further comparison between Al(Ga)N/GaN based devices, ISFETs with smaller sensitive area (35 x 35 m2), similar to the ones used in cellular activity record, were fabricated and characterized. When the devices are subjected to a voltage pulse through the sensitive area, the response of AlN based devices shows lower noise than the ones based on AlGaN. The noise in the current of such a AlN based device, where the encapsulation has not been optimized, is as low as 8.9 nA (rms value), and the equivalent noise to the surface potential is 38.7 V. These values are lower than the found in typical devices used for cellular activity recording (based on Si), and in the range of the best published results on AlGaN/GaN. From the point of view of the electrochemical characterization of GaN and InN surfaces, their isoelectric point has been experimentally determined. Such a value is the first time reported for GaN and InN surfaces. These values are determined by “streaming potential”, being pH 4.4 and 4, respectively. Isoelectric point value is an important characteristic in sensors, electrostatic immobilization or in colloidal lithography. In particular, colloidal lithography has been optimized in this Thesis for GaN surfaces, and applied in the last part of experimental results (i.e. ordered growth). The last block of this Thesis is focused on the selective area growth of GaN nanocolumns by MBE, using Ti masks decorated with nanoholes. The effect of the different growth parameters (Ga and N fluxes, growth temperature and mask design) is studied, in particular their impact in the selectivity and in the morphology of the nanocolumns. Selective area growth has been successful performed on GaN templates with different orientation or polarity; GaN(0001)/sapphire, GaN(0001)/AlN/Si, GaN(000- 1)/Si and GaN(11-20)/sapphire. Ordered nanocolumns exhibit a high crystal quality, and a higher thermal stability (lower thermal decomposition) than the compact layers of the same material. Ordered nanocolumns based on III nitrides have a clear application in optoelectronics, mainly for white light nanoemitters. However, this Thesis proposes them as an alternative to compact layers and self-assembled nanocolumns in sensor applications. Self-assembled GaN nanocolumns are very appealing for sensor applications, due to their large surface/volume ratio. However, their large dispersion in heights and diameters are a problem in terms of processing and operation of real devices. In this aspect, ordered nanocolumns are more robust and homogeneous, keeping the large surface/volume ratio. As first experimental evidence of their sensor capabilities, ordered nanocolumns have been studied regarding their photoluminiscence on air and vacuum ambient. A big drop in the intensity is observed when the nanocolumns are exposed to air (probably because of the oxygen photo-adsortion), as was already reported in the case of self-assembled nanocolumns. This opens the way to future sensors based on ordered III nitrides nanocolumns.

Thermally assisted tunneling transport in La0.7Ca0.3MnO3/SrTiO3:Nb Schottky-like heterojunctions

We report on the electrical transport properties of all-oxide La0.7Ca0.3MnO3/SrTiO3:Nb heterojunctions with lateral size of just a few micrometers. The use of lithography techniques to pattern manganite pillars ensures perpendicular transport and allows exploration of the microscopic conduction mechanism through the interface. From the analysis of the current-voltage characteristics in the temperature range 20-280 K we find a Schottky-like behavior that can be described by a mechanism of thermally assisted tunneling if a temperature-dependent value of the dielectric permittivity of SrTiO3:Nb (NSTO) is considered.We determine the Schottky energy barrier at the interface, qVB = 1.10 ± 0.02 eV, which is found to be temperature independent, and a value of ? = 17 ± 2 meV for the energy of the Fermi level in NSTO with respect to the bottom of its conduction band.

Ultra high frequency thin film saw devices

Durante los últimos años el flujo de datos en la transmisión que tiene lugar en los sistemas de comunicación ha aumentado considerablemente de forma que día a día se requieren más aplicaciones trabajando en un rango de frecuencias muy alto (3-30 GHz). Muchos de estos sistemas de comunicación incluyen dispositivos de onda acústica superficial (SAW) y por tanto se hace necesario el aumento de frecuencia a la que éstos trabajan. Pero este incremento de frecuencia de los dispositivos SAW no sólo es utilizado en los sistemas de comunicación, varios tipos de sensores, por ejemplo, aumentan su sensibilidad cuando la frecuencia a la que trabajan también lo hace. Tradicionalmente los dispositivos SAW se han fabricado sobre cuarzo, LiNbO3 y LiTaO3 principalmente. Sin embargo la principal limitación de estos materiales es su velocidad SAW. Además, debido a la alta temperatura a la que se depositan no pueden ser integrados en la tecnología de fabricación CMOS. El uso de la tecnología de capa delgada, en la que un material piezoeléctrico es depositado sobre un substrato, se está utilizando en las últimas décadas para incrementar la velocidad SAW de la estructura y poder obtener dispositivos trabajando en el rango de frecuencias requerido en la actualidad. Por otra parte, esta tecnología podría ser integrada en el proceso de fabricación CMOS. Durante esta tesis nos hemos centrado en la fabricación de dispositivos SAW trabajando a muy alta frecuencia. Para ello, utilizando la tecnología de capa delgada, hemos utilizado la estructura nitruro de aluminio (AlN) sobre diamante que permite conseguir velocidades SAW del sustrato que no se pueden alcanzar con otros materiales. El depósito de AlN se realizó mediante sputtering reactivo. Durante esta tesis se han realizado diferentes experimentos para optimizar dicho depósito de forma que se han obtenido los parámetros óptimos para los cuales se pueden obtener capas de AlN de alta calidad sobre cualquier tipo de sustrato. Además todo el proceso se realizó a baja temperatura para que el procesado de estos dispositivos pueda ser compatible con la tecnología CMOS. Una vez optimizada la estructura AlN/diamante, mediante litografía por haz de electrones se fabricaron resonadores SAW de tamaño nanométrico que sumado a la alta velocidad resultante de la combinación AlN/diamante nos ha permitido obtener dispositivos trabajando en el rango de 10-28 GHz con un alto factor de calidad y rechazo fuera de la banda. Estás frecuencias y prestaciones no han sido alcanzadas por el momento en resonadores de este tipo. Por otra parte, se han utilizado estos dispositivos para fabricar sensores de presión de alta sensibilidad. Estos dispositivos son afectados altamente por los cambios de temperatura. Se realizó también un exhaustivo estudio de cómo se comportan en temperatura estos resonadores, entre -250ºC y 250ºC (rango de temperaturas no estudiado hasta el momento) diferenciándose dos regiones una a muy baja temperatura en la que el dispositivo muestra un coeficiente de retraso en frecuencia (TCF) relativamente bajo y otra a partir de los -100ºC en la que el TCF es similar al observado en la bibliografía. Por tanto, durante esta tesis se ha optimizado el depósito de AlN sobre diamante para que sea compatible con la tecnología CMOS y permita el procesado de dispositivos trabajando a muy alta frecuencia con altas prestaciones para comunicaciones y sensores. ABSTRACT The increasing volume of information in data transmission systems results in a growing demand of applications working in the super-high-frequency band (3–30 GHz). Most of these systems work with surface acoustic wave (SAW) devices and thus there is a necessity of increasing their resonance frequency. Moreover, sensor application includes this kind of devices. The sensitivity of them is proportional with its frequency. Traditionally, quartz, LiNbO3 and LiTaO3 have been used in the fabrication of SAW devices. These materials suffer from a variety of limitations and in particular they have low SAW velocity as well as being incompatible with the CMOS technology. In order to overcome these problems, thin film technology, where a piezoelectric material is deposited on top of a substrate, has been used during the last decades. The piezoelectric/substrate structure allows to reach the frequencies required nowadays and could be compatible with the mass electronic production CMOS technology. This thesis work focuses on the fabrication of SAW devices working in the super-high-frequency range. Thin film technology has been used in order to get it, especially aluminum nitride (AlN) deposited by reactive sputtering on diamond has been used to increase the SAW velocity. Different experiments were carried out to optimize the parameters for the deposit of high quality AlN on any kind of substrates. In addition, the system was optimized under low temperature and thus this process is CMOS compatible. Once the AlN/diamond was optimized, thanks to the used e-beam lithography, nanometric SAW resonators were fabricated. The combination of the structure and the size of the devices allow the fabrication of devices working in the range of 10-28 GHz with a high quality factor and out of band rejection. These high performances and frequencies have not been reached so far for this kind of devices. Moreover, these devices have been used as high sensitivity pressure sensors. They are affected by temperature changes and thus a wide temperature range (-250ºC to 250ºC) study was done. From this study two regions were observed. At very low temperature, the temperature coefficient of frequency (TCF) is low. From -100ºC upwards the TCF is similar to the one appearing in the literature. Therefore, during this thesis work, the sputtering of AlN on diamond substrates was optimized for the CMOS compatible fabrication of high frequency and high performance SAW devices for communication and sensor application.

E-beam nano-patterning for the ordered growth of GaN/InGaN nanorods

E-beam lithography was used to pattern a titanium mask on a GaN substrate with ordered arrays of nanoholes. This patterned mask served as a template for the subsequent ordered growth of GaN/InGaN nanorods by plasma-assisted molecular beam epitaxy. The mask patterning process was optimized for several holes configurations. The smallest holes were 30 nm in diameter with a pitch (center-to-center distance) of 100 nm only. High quality masks of several geometries were obtained that could be used to grow ordered GaN/InGaN nanorods with full selectivity (growth localized inside the nanoholes only) over areas of hundreds of microns. Although some parasitic InGaN growth occurred between the nanorods during the In incorporation, transmission electron microscopy and photoluminescence measurements demonstrated that these ordered nanorods exhibit high crystal quality and reproducible optical properties.

Fabrication of GaN nanorods by focused ion beam

Ordered arrays of III-Nitride nanocolumns are excellent candidates for the fabrication of nano-optoelectronic devices. Different technologies such as e-beam lithography or colloidal lithography, have been used to obtain ordered arrays. All these technologies have in common several processing steps that can affect the crystalline growth of the nanocolumns. In this work, we present a single lithographic step that permits to grow ordered GaN nanocolumns with different geometries. The patterning is based in the use of a focused ion beam with different doses. With this method has been possible to create GaN nanopillars and nanocylinders.

Ferromagnetic resonance and magnetooptic study of submicron epitaxial Fe(001) stripes

We present a combined magnetooptic and ferromagnetic resonance study of a series of arrays of single-crystalline Fe stripes fabricated by electron beam lithography on epitaxial Au(001)/Fe(001)/MgO(001) films grown by pulsed laser deposition. The analysis of the films revealed a clear fourfold magnetocrystalline anisotropy, with no significant presence of other anisotropy sources. The use of a large series of arrays, with stripe widths between 140 and 1000 nm and separation between them of either 200 nm or 500 nm, allowed studying their magnetization processes and resonance modes as well as the effects of the dipolar interactions on both. The magnetization processes of the stripes were interpreted in terms of a macrospin approximation, with a good agreement between experiments and calculations and negligible influence of the dipolar interactions. The ferromagnetic resonance spectra evidenced two types of resonances linked to bulk oscillation modes, essentially insensitive to the dipolar interactions, and a third one associated with edge-localized oscillations, whose resonance field is strongly dependent on the dipolar interactions. The ability to produce a high quality, controlled series of stripes provided a good opportunity to achieve an agreement between the experiments and calculations, carried out by taking into account just the Fe intrinsic properties and the morphology of the arrays, thus evidencing the relatively small role of other extrinsic factors.

Nano-imprinted rear-side diffraction gratings for absorption enhancement in solar cells

As wafer-based solar cells become thinner, light-trapping textures for absorption enhancement will gain in importance. In this work, crystalline silicon wafers were textured with wavelength-scale diffraction grating surface textures by nanoimprint lithography using interference lithography as a mastering technology. This technique allows fine-tailored nanostructures to be realized on large areas with high throughput. Solar cell precursors were fabricated, with the surface textures on the rear side, for optical absorption measurements. Large absorption enhancements are observed in the wavelength range in which the silicon wafer absorbs weakly. It is shown experimentally that bi-periodic crossed gratings perform better than uni-periodic linear gratings. Optical simulations have been made of the fabricated structures, allowing the total absorption to be decomposed into useful absorption in the silicon and parasitic absorption in the rear reflector. Using the calculated silicon absorption, promising absorbed photocurrent density enhancements have been calculated for solar cells employing the nano-textures. Finally, first results are presented of a passivation layer deposition technique that planarizes the rear reflector for the purpose of reducing the parasitic absorption.

Scaling of the coercivity with the geometrical parameters in epitaxial Fe antidot arrays

We studied a series of square lattice antidot arrays, with diameter and lattice parameter from hundreds of nanometers to some microns, fabricated using two lithography techniques in epitaxial Fe(001) films. The coercivity increase of each array with respect to its base film can be scaled to a simple geometric parameter, irrespective of the lithography technique employed. Magnetic transmission x-ray microscopy studies, in arrays fabricated on polycrystalline Fe films deposited on silicon nitride membranes, evidenced the propagation of reversed domains from the edges of the arrays, in agreement with the coercivity analysis of the epitaxial arrays and with micromagnetic models.

Full-Wafer Roller-NIL Processes for Silicon Solar Cell Texturisation

The highest solar cell efficiencies both for c-Si and mc-Si were reached using template based texturing processes. Especially for mc-Si the benefit of a defined texture, the so called honeycomb texture, was demonstrated impressively. However, up until now, no industrially feasible process has been available to pattern the necessary etching masks with the sufficient resolution. Roller-Nanoimprint Lithography (Roller-NIL) has the potential to overcome these limitations and to allow high quality pattern transfers, even in the sub-micron regime, in continuous in-line processes. Therefore, this etch-mask patterning technique is a suitable solution to bring such elaborate features like the honeycomb texture to an industrial realization. Beyond that, this fast printing-like technology opens up new possibilities to introduce promising concepts like photonic structures into solar cells.