I am working on thin film semiconductors. From XRD results what I observed is an increase in the crystallite size with an increasing temperature. Can I say an increase in the crystallite size is an indicative of an improvement in the crystallinity of the films? is there any relation between the crystallite size and crystallinity?
From my understanding, crystallite size and crystallinity are generally independent of each other but both are potentially affected by temperature depending on the material you are working with and your processing methods. I think of crystallinity as the arrangement and order of molecules/atoms while the crystallite size has to do with how many atoms/molecules are arranged in a crystallite. You can have a large crystallite that is highly crystalline but you can also have a large crystallite that has low crystallinity and vice versa for small crystals. The two things occurring are nucleation (birth=arrangement or rearrangement of atoms from parent phase to daughter phase) and crystal growth (growth=the increasing size of a pre-existing crystal structure after the initial nucleation) -- both depend on the thermodynamics and reaction kinetics.
Shaik Babujani
I think you should consider that during the increase in temperature the film undergoes a heat treatment which can increase the crystallinity of the compound - this does not necessarily depend on the crystal size .
Dear all, at which step you are increasing temperature ? Annealing (post-preparation thermal treatment) is a way to enhance both crystallites size and perfection. These authomatically increase % crystallinity. My Regards
Dear Shaik Babujani
Crystallinity increase when the molecules are arranged (or bundled) together (Like Spaghetti at its plastic package), when you lose this molecular arrangement, you gain an amorphous materials (cooked Spaghetti + water : like Chinese LaMian noodles).
Please understand that the unit of the "Crystal size" is for length not volume (how long distance is occupied your crystallite). Here, the crystal growth is taking place.
==> Molecule is a long chain. They meet each other "to gathered" together at one "Society" (= making a Crystal).
==> How this crystal BORN? is: a nucleation matter
==> How this crystal GROW up? is: a crystal growth matter
I am agreeing with the above mentioned answers. by Genesis Marrero , Carlos Ariel Samudio Pérez and Abdelkader BOUAZIZ. There is NO relationship btwn the crystal size and crystallinity. You need to check the influence of each process on the physical property of you sample
Wishing you all the best
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