pulsed laser deposition

[Guest souiss]

Hi everyody,

I intend to buy a pulsed laser depostion (PLD) setup to deposit thin ceramic films. By reading the litterature it seems that a lot of people use KrF lasers with a wavelength of 248nm. However using a solid-state Nd:YAG laser whose frequency is quadrupled (1064nm down to 266nm) seems to be also possible.

What are the pros and the cons concerning the use of a KrF gas laser and a Nd:YAG solid-state laser to work around 250nm for deposition of thin oxide films?

Thanks in advance for your help and for sharing your experience of PLD.

Souiss

[Cap'n Refsmmat]

As you can tell, most of us are thinking, WHAT?!!

[Radical Edward]

I would imagine that an excimer laser would be more tricky to run, and you would have to replace the KrF more often than the YAG laser rods. the YAG would just use some harmonic crystal to produce the nonlinear effects, but then you might not get as much power out of this as the susceptibility of most nonlinear materials is not all that high. Either way round, it will be pretty expensive, and I hope you know what you are doing. KrF lasers, are by default class 4 since they produce high levels of invisible radiation and would blast your eyes out without proper protection. This is only a brief explanation, I only really have a theoretical knowledge of most lasers, and have only worked personally with Argon Ion lasers (as well as the usual university ones like HeNe) so I can't help alot.

 

I do have to ask though, do you know what you are doing with lasers and do you have much experience with running them and a good knowledge of all the safety requirements?

[YT2095]

Go with the YAG!, it`s use succesfully for laser ablation all the time, the KrF cuvetes (or what ever your pulse media is stored in will need frequent changing as stated above as will the media).

YAGs rock!

pulsed CO2 is the next best at a slightly higher cost initialy, but after that wattage per buck it`s your best bet.

the frequency of course is very important, the higher the freq the greater the activation or quanta per packet, but that all depends on the material you wish to vaporise, YAG`s don`t have to be solid state either!

[Radical Edward]

you haven't got a YAG in your lab have you?!?!

[YT2095]

I did have a few years ago yeah, why do ya ask?

[Radical Edward]

lol cool, what class was it? what did you do with it?

[YT2095]

it was only a little class 4 ( just under a couple of watts).

what didn`t I try and do with it LOL

[Radical Edward]

did you try any frequency doubling or pulse compression, or mostly just burning stuff?

 

Reminds me of an ace little story. Me and a mate were coating mirrors for our Argon Ion laser experiment, and we needed Liquid Nitrogen for the vacuum pump. Anyway our supervisor just told us where the huge vat of the stuff was, and let us use it as we felt fit. Of course what ensued was us wandering round the lab hurling this stuff at one another, and freezing random things, but anyway once it went a bit wrong, and some of it shot out into the corridor and under someone's door, and seconds later an irate researcher stormed into our lab askin what we were doing. I am stood there frozen to the floor (it went under my shoes and stuck the rubber down a bit), and my mate is stood there with a big grin and an empty Nitrogen flask "Nothing" we reply. Fortunately the irate researcher didn't really mind, and told us that it was a good way to clean the dust up from the floor.

[YT2095]

it had a frequency doubler built in (the unit was the size of a small fridge) but I don`t think it worked? either that or I couldn`t figure out how to use it (both are likely, LOL).

I got it in the early 90`s about 93 I think it was, had it for a few years, and there WAS some stuff I couldn`t figure out on it, it was *ehem* "Second hand" equipment, that happened to follow a friend of mine all the way back home with him from a demolition job, it cost me 50 notes

 

yeah I did the setting fire to news paper across a room stuff

as well as litter outside my lab in the streets

nearly blinded myself above once! had several trips to the hospital being treated for "The Flash" (arc welders will know what thats like!).

zapped many a house fly, removed a wart, accidently made a patch on my chin that no beard will ever grow now, tried to hit the moon (I don`t even know why, it wasn`t like it was likely to DO something), ruined serveral pairs of jeans, tried to make a laser feild in a doorway with mirrors (as I say, I nearly blinded myself above once!). I could continue

the only scientific work I actualy did was try to bridge the gap between an electrical charge, using the ionised path from the laser It worked btw

 

other than that, no, I was like a kid with a new and dangerous toy

 

 

(I was only 26 at the time tho!)

[Radical Edward]

sounds cool. I would probably be more likely to do optics related stuff with a laser though, but I think I would need a sputtering system to make mirrors too. Shame you didn't patent the beard thing though, you could well have ben onto laser hair treatment there before anyone else (though maybe not, I am not sure how long it has been around)

 

we had some excellent cartoons around our laser labs..

 

Laser Tag (below a picture of a scientist with a hole through his middle)

 

Peer Pressure (Below a picture of a new scientist, wandering round a lab full of scientists with an eyepatch)

 

and the ever famous note on laser lab doors:

 

"Please do not look into Laser with remaining eye"

[YT2095]

LOL

 

to be completely honest, I didn`t have much in the way of Lab kit back then and optics were out of the question really, I was even using a homemade telescope. being on the dole, I hadn`t got alot of cash (lots of ideas, just no finance).

 

as for your liquid nitrogen exploits, I`de love to have had a mess around with that stuff

the best I`ve ever played around with has been dry ice (CO2), I can get it quite easily from Carlos, the guy in the ice cream van

as for the beard thingy, I was a zitty teenager loads of spots, and some left a few scars, so I figured after reading a few surgical manuals ( I was doing that anyway) I came across scar removal by Laser, so I thought I`de have a go LOL, it kinda worked! but now there`s a patch that grows no beard, good thing I don`t want one anyway!