In XRD (even tho i did GI-XRD i got substrate peaks also in the patterns) patterns usually intensity of the substrate peaks should decrease with increase in the film thickness because of more reflections from the film than the substrate but in my case substrate peaks intensity increases(intensity of the film peaks also increases) with film (poly crystalline film) thickness
So what could be the reason for increase of substrate peaks intensity ? and apart from film thickness which factors( like porosity ,voids ,roughness etc) will effect the substrate peak intensity ?
My only thought at this time is to ask what grazing angle you are using and is it the appropriate one for your substrate. Can you post the XRD patterns to give an idea of how they change?
Which substrate you are using.. Roughness will affect the peak intensity..
I think you are doing the measurement at high angles so try to do the measurement at low incident angles.....
You might wish to consult this paper: http://x-server.gmca.aps.anl.gov/pub/Stepanov_Smolenice_1997.pdf
Please optimize your incident angle carefully, it's very important for GI-XRD.
Dear Smruthik Kumar
Have a nice time and good day
I think that you have something wrong, because increasing the film thickness leads to decrease the intensity of substrate peaks. It may be the discontinuity of the film texture, the large porosity of samples, great voids or the roughness of the substrate.
.Good luck
@Alok Kumar Pandey : I am using Pt(111)/TiO2/SiO2/Si substrate. It roughness is around 5 nm. Even roughness will effect the Peak intensity, I think that won't applicable in my case because melting point of Pt is very high. and i did deposition at 750 deg C(maximum)
@ Joseph S Merola and @ Ahmed Saeed Hassanien
Thank you for your suggestions..
Sometime we think our film thickness increased with the increase of ie. time, cycle etc. Make sure your film thickness really increase by measuring cross section SEM. Or you can use other method to make sure the thickness of your film. After you are sure your film thickness, check your XRD parameter measurement ie the covering of XRD beam. If your film thickness is very small then the XRD reflection may be come from the substrate or at least there are the contribution peak from substrate. I hope it is not because of the film texture, the large porosity of samples, great voids or the roughness of the substrate as other opinion. Regards
Dear posman Manurung,
First of of all thank you for your suggestion. I am sure sir, film thickness increased. I measured the film thickness from the cross section FESEM images by using IMAGE J software. I also calculated crystalline size from XRD ( of course there is so many other contribution also there in it such as instrumental brodening, strain etc ). Crystalline size also increases with temp. So this is resembles to the FESEM data..
One other possibility is that you have significant pores in your new layer and so the underlayer becomes more exposed.
re Joseph Merola, "One other possibility is that you have significant pores in your new layer and so the underlayer becomes more exposed."
Yes, that's what I thought, too. And, somwhat counterintuitively, the pores can grow with greater thickness (surface tension and heating during deposition).
But I would not expect such pores to also increase substrate signal in GIXS.
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