Peeling Graphite to produce graphene / Desmenuzando Grafito para producir grafeno

Hope this process is helpful, some how for you. I start to write this section in English and Spanish, may be later I'll include also P'urhépecha...

Continuing with the process or the first step to develop devices based on graphene, well the cheapest way to do it is by using Graphite, yes the same, sort of, graphite as you use in daily basis to write with your pencil, well the same with the main difference that the graphite used for this purposes is high quality and free of any contamination from other elements or materials.

There are a sequence of steps that we have to follow prior to start:
1.- We need to have high quality graphite, there are several companies that supply this material, her the quality changes according of how much money do you want to pay. If flakes of few mm or cm (cheap), if flakes of few microns to mm, lets say a bit expensive.
2.- Cut tape in strips (10 cm in length x 2 - 4 cm width). Usually in papers you can read that some people used Scotch tape, well thats rubbish!, almost any tape (that is used within a cleanroom in general blue tape) is enough to do this process.
3.- probably the most important in this pre-preparation are the samples with a thin SiO2 layer (90 nm). It is possible to prepare them by using a highly doped p+ Si substrate wafer, oxidised it to grow 90 nm of SiO2 and patterned it with coordinates and contacts with gold in a 5 mm x 5 mm dice.

Once we have prepared those elements we,re ready to start with the peeling ;)

First, in one edge of the tape deposits a small amount of graphite or a few flakes to start with the process as shown in picture

We start by pressing the side that contains the graphite pieces with the "clean" side of the tape, make the process to look as if we want to pass the major quantity of graphite into the clean part of the tape. By doing this step several times, it will have the follow appearance

In here it is possible to see that the graphite flake has been dusted over the tape. This process (as I'm not an expert in this process, yet) took me few minutes and few tape stripes to get it. With time and experience  it is possible to have a better graphite dust quality. By continuing doing this process, after few other stripes and a few more, we can get a strip that looks like

The silver-ish colour that the picture shows is the remains of graphite flakes that now we can start to call it as few graphene layers material ;P. This process is continuing doing by other two or three tape stripes until we obtain an uniform silverfish stripe tape colour. It is fair to pointed out that when silver-ish colour the sticky tape becomes as electrostatic tape, when we reached this point it is indicative that we need to change the tape and continuing with the process or to put the sample and softly remove the denser section of the tape into the sample... but that is for the next chapter ...

To be continued ...

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Iniciando o continuando con el proceso de cómo preparar muestras de grafeno utilizando grafito como materia prima. Primeramente debemos definir o decir que es el grafito, grafito es un material que tiene como base al carbono y que normalmente se encuentra en la punta de los lápices que comúnmente utilizamos en las escuelas para escribir o resolver ecuaciones. En teoría la punta de un lápiz y el material que estaremos utilizando para fabricar dispositivos electrónicos es similar. La única diferencia radica en que el material que utilizaremos será de una pureza muy alta y con un precio también un poco elevado. Existen varios tipos de grafito, el cual depende en gran medida del precio que se quiera pagar por él. Si se compran pedazos que van de algunos mm hasta un cm el precio es, digamos, aceptable (algunos cientos de euros/dólares/libras, miles de pesos :'( ). Bueno para preparar nuestra muestras de grafeno, nosotros requerimos de varios materiales previamente preparados y en la mesa de trabajo (dentro del cuarto limpio) antes de iniciar con nuestro proceso:

1.- Primeramente necesitamos contar con grafito ya sea de my alta calidad o de baja calidad, esto que da a discreción y bolso de cada laboratorio o grupo de trabajo. Normalmente se utiliza grafito de alta calidad (industria Japonesa) que por varios cienos de gramos se pueden llegar a pagar algunos miles de libras y allí la dejamos.
2.- Se necesita cortar en tiras de 10 cm x 2 a 4 cm cinta industrial, en algunas publicaciones ponen que es cinta escocesa o Scotch tape, digamos que esas son ... tonterias... cualquier cinta que se utilice en el laboratorio (azul) se puede utilizar dentro de este proceso.
3.- Uno de los puntos angulares con los que debemos contar es con dados o muestras de Si/SiO2 que tengan un espesor de aislante de 90 nm. En varias publicaciones se demuestra que con estos espesores el grafeno de hasta varias capas es visible. Entonces se debe contar con estas muestras la cuales deben contener también una matriz maleada y contactos depositados en oro. El proceso que se utiliza normalmente para este trabajo es e-beam y lift-off.

Una es que contamos con nuestros utensilios iniciamos con nuestro proceso. Aquí en una de las puntas de la cinta previamente cortada ponemos algunos pedazos de grafito como se observa en la imagen

Se toma el extremo de la cinta que contiene los pedazos de grafito y se pega con el extremo que esta limpio, siempre tratando de pasar la mayor cantidad de grafito. Después de varias veces de realizar este procedimiento, la muestra se verá como

Aqui vemos que se ha distribuido y se ha desgajado el grafito que inicialmente se había depositado obre la cinta. Al repetir este proceso por otras 4 ó 5 cintas, se observa que la densidad de granos de grafito disminuye y se observa que éste se va haciendo más laminar. Al continuar rebajando los granos de grafito, nos encontramos con que el grafito ya no es granular sino laminar y se obtiene

En esta imagen se observa un color silverado del grafito que a partir de ahora se denomina grafeno (muchas capas) pero de grafeno. Al obtener este tipo de color y estructura, estamos seguros que vamos por el camino de obtener (con mucho trabajo, experiencia y paciencia) monocapas de grafeno. Al continuar con este proceso por otras dos ó tres veces, es posible encontrar una cinta con una alta densidad de graneo sobre ella, la cual es suficiente para vaciarla sobre las muestras que ya habíamos preparado, pero esa es otra historia ....

Continuará ...

Mario A.

Winchester, first Spring day off

Yesterday we went out for a trip after this winter season almost finishes ... Everything started with a proposition made b Karola, she wanted to go to see an exposition of a painter, so as we were also interested we say, why not? then we agree and start to make plans.

When the day arrived I received a call in the morning quite aryl (9 am), Karola called me and asked me if I was willing to join them, I say yes, she also ask if I can invite others, so I called Juan . . .  after few time and as he didn't respond, I sent him a message in which I explaining him what we want to do that day.. later he replies and say that he want t come.. so I let him know that we were meeting at 12 in central station.

After we arrive there, late, ah, I forgot to mention that I called early that day Faby and asking her to go walking to the train station, she agrees and ... after 20 min, she say it is better if we just cal a taxi... well making this story short, we took the bus and reach on-time to the train station just to know that Juan was arriving late and we have to wait for him. So, the other chaps left on time and went to Winchester to enjoy of that marvellous day. We went for a coffee within the station in which, surprisingly is now renew, it looks so nice, I even can say that posh, but it is FAKE!!! the bloody couch that looks so nice to be there for a while, in reality is so cheap that if you just seat in a hurry, you're going t brake your backbone because the couch is so CHEAP!!! so, if you're reading this and you;re willing to sit at Southampton central in line 1a, please be aware that you might have an accident.

Once Juan arrived, we wait for the next train and we moved to Winchester, in there already were waiting for us the other guys. As we were already hungry (13.30 hrs ish), we agree to go to an old pub in the red light district by the end of the cathedral (as you do), and as the day was so nice, sunny, a bit chilli but not quite to be aware of wear a sweater, we just enjoy the day. when arrived to the place, it was already fully booked apart from the bar and the garden, the grade, a group f  Polish and Mexicans, that was just magnificent. Once int he grade we had a rather amazing chat and of course few pints. The food in this place is quite posh and in all these places in which food is good, is just a bit. So, most of us we were already disappointed by the quantity but quality.

Once we move out of that pub, one girl of the group wanted to go to the cathedral, WTF!!! yes, and you know EVERYTHING in UK is not free, so as usual if you waned to go inside you have to pay. As we DON't of course, we didn't pay and we didn't go inside of course despite the fact that just that girl waned to go and all of us well, just make fun of it loudly!!!!

We move to high-street in order to find a new pub in which get a taste of a delicious beer. For our surprise and mine in particular, there was a girls singing opera, yes a few arias in the middle of the street. I was gladly surprise about this event, the girl wasn't too bad and the arias that she was playing were so pleasant for the time and for her voice. Once her performance finished, we move to a pub by the river the shepherd  something. It has a huge warden that goes directly into the river path. In there we got few beers, coffee, chocolate and ... few pics.

At that moment we decided that if we return to Soton early we can not made to go inside of the Polish performance so, we stayed and walt y the river, watching, smelling, walking, making jokes, a rather nice evening. When dark comes, we move to teen station and went back to Soton.

A really lovely day, the first of many in this Spring.

Valencia y sus alrededores ... con ¡el Ajo y el Miguel!

Al final del año pasado me aventuré a finalmente conocer el lugar en el que el buen Miguel y la Ajo viven y trabajan (ja) bueno Miguel sí. Para iniciar tuve que apartarlos un par de días y molestarlos durante más ao menos una semana o cinco días o algo así. En fin, como no hay plazo que no se cumpla ni fecha que no se llegue, me lancé a la buena España a conocer esa área. Anteriormente había estado por esas tierras pero por el área de Barcelona, cerca de allí en el área de Andalucía visitando Granada, Sevilla, etc. En fin, me fascinó lo que ví por allá además de la comida, clima y claro la compañía que organizó el viaje, eso fue lo más mejor :D.

En fin, salí en la madrugada de Soton para llegar a tiempo al aeropuerto de Gatwick. En fin llegué rayando y tomé el vuelo. Llegando a Valencia, allí ya estaban esperandome los Ajos y me esperaron con más que mejor recibimiento que un buen cafe 'corto'. De allí nos aviemos a su piso, si u par de meses y ya cambian la nomenclatura a todo (como era de esperarse). A partir de allí fue, recordar viejos tiempo con la Ajo, entiéndase a fregar, fregar, fregar y más fregar, 'pobre Miguel'.

Salimos a caminar por el pueblo, tiene un mega parque el cual está seccionado en infinidad de partes para practicar infinidad de deportes y todo, sin estar controlado, pero, de alguna manera funciona. Algún día después el Miguel se lanzó a su trabajo y el Ajo y yo nos fuimos a la zona súper turística de Valencia. Ese lugar es ... simplemente apantallante.

Si tienen planeado irse de vacaciones y están por las Europas, desde un tiempo para visitar Valencia, es un lugar súper tranquilo, ni está tan caro como otros lugares de España como Barcelona o Madrid que si lo pueden estar.

En fin, aquí les dejo un video de nuestro regreso desde la zona cerca de la playa hasta ... donde me alcanzó la batería del celular.

Mario A.

Como instalar dos monitores en Linux Ubuntu 8.04 . . .

Hoy, después de una muy larga espera, volvía a utilizar mi vieja versión de Linux (Ubuntu 8.04), s;i, lo se, es bastante vieja, pero muy estable para lo que la he necesitado. Desde que le puse dos monitores a mi máquina, allá por el Pleistoceno tardio, hoy me dí a la tarea de implementar los dos monitores y trabajar o lo que eso signifique. Para aquellos que quieran experimentar en usar dos monitores bajo linux, bueno al menos en ubuntu, aquí están los pasos:

1.- Descargar el paquete: EnvyNG usando el Synaptic Package Manager, aquí te dará la opción de incluir también las extensiones envyng-core y envyng-gtk, dónde core es el programa y el gtk es la interfase

2.- Abrir el programa que está en herramientas del sistema, una vez que lo hayas llamado, te va a pedir tu contraseña de inicio, esto porque debe instalar algunos programas en tu cuenta. Te presentará ds opciones a instalar, una es Nvidia y la otra ATI. Selecciona la que se encuentre en tu máquina y si por alguna razón (que no se me ocurre alguna si usas linux) revísala en el sistema :). Una vez seleccionada, selecciona que instale todo el sistema por default, esto hará que instale la versión más estable y la más robusta. Esto puede tomar un tempo, en función de que tan rápida pueda ser tu conexión de internet, después de haberse instalado, debes reiniciar tu máquina.

3.- Una vez reiniciada tu máquina, ve a sistema y en administración selecciona NVIDIA X server settings,   aquí selecciona una vista dual, aplica, aquí te mostrará como se verá tu máquina con dos monitores, selecciona las resoluciones y ... disfruta. Una vez que salves, rebootea y listo, si por alguna razón no se ven bien los dos monitores, ve a sistema, preferencias y en screen resolution, fijare que no este seleccionado clon e serenes y .. listo ...

Mario A

Graphene peeling proces 101 . . .

After read loads of papers, thesis, manuals, among many other kind of visual literature, today I finally start to work with graphed, my first work was based on a simple and, in todays world, a normal graphed flakes process based on the already well known (I really dislike this word) scotch tape process developed by many and improved by Novoselov et al. It f fair to say that the chap that told me how to do it, despite have had a discrepancy in ideas, is a not bad teacher at all.

At the same time I developed a 1 mm^2 for a new chip in which I'm working with, lets see how can I propose some designs ...

Mario A

High-qualified slave

The entire life plenty of people is asking what to do when finally after 10, 20 or more years of study are near to finish. In my case as in many others in my lab, group, school when the final week is finally there, I mean when you PhD exam or viva as in the UK like (in a bizarre way) to call is just few days ahead. Is presumably the same feeling as a woman is having when is final near to get married and a t some point we all share the same mythic feeling, we just care about the "DAY" that this even is going to happen, we basically don't care (and to be fair we are abstracted from space and time) about what is happen in the other room, bay or office. Moreover, a distortion in space ad time is having a twisted sense of humour. when reading the thesis and you fins something that is not quite correct the time rushes and suddenly three hours are whole day or you read whole thesis, several paper, all newspapers and .. in just 30 minutes!!! bloody efficiency batman!

But, what happen the next day, after the viva? we are not students anymore by any bizarre mean, suddenly we are unemployed, broken, without holidays, suddenly a bunch of debts appear, letting a place is not easy anymore and to make it worse ... in the lab, where always was enough resources to work endlessly, to buy everything, to go to any conference ... in a simple moment there is no money to hire for a few month a fresh PhD!!! the only plausible option to keep your old sit, your space is to become a new sub-specie ... a brand new high-qualified slave!!! You've more responsibilities, you're the leader for some new guys, you've to be responsible for a huge amount of documents to report, student to push and work that have to be done at lab and even more, all this ..... taran .....for free!!!

Yep, at the moment that is my status, that was the status of many other friends and eventually it will be your status (if you're attempting for a PhD degree) until the new open position season is open. This slavery time will last for few month or till you die, any of them we're screwed.

Mario A

When you're applying to work in a different part, country, culture, continent, even street, there are a lot of small things such as language, time zones, people, IP addresses or even the simple and even vulgar keyboard that ... by some miserable and useless portion of time IT DOESN'T WORK!!!!!! I'm applying for a position in a place in which, by definition should have, lets say ... a multi-cultural, recognisable and bloody simple interface but NO!, instead the bloody website is in a native language that .... only the people from that country in particular can fill and even though those chaps cannot fluently understand....

Anyway, this is part of apply for a time-dependent position... while in Mexico ... well there are people doing whatever they need to avoid working in favour of the people ...