We grow single crystals for nonlinear optical applications. to check the quality of the grown crystal we go for defect analysis such as vacancy, point and line defects. from compositional analysis we can easily find out the vacancy defects. From high resolution X-ray diffraction (HRXRD) measurements we can easily find the vacancy and point defects. from positron annihilation studies we can find out the point defects. is there any possible to find the defect analysis using SEM analysis?
I am afraid that it is not possible to fine the line defects using sem analysis, because the resolution of sem is normally larger than 1 nm, much beyond the size of line defects.
Thank you Prof. Jianhui Liao and Dr. David Mercier for your answers.
It's very difficult to probe the nature of defects using SEM except you may get some idea about growth pattern and terrace arrangement. SEM imaging is a rough sketch by reflected electrons
SPM (AFM, STM) and confocal microscopy are the recommended techniques to know about the extrinsic defects. However to know the intrinsic defects you should have idea about crystal growth mechanism which can be known by slicing the crystal and analysing by AFM can also help to find the pattern and defects.
"From high resolution X-ray diffraction (HRXRD) measurements we can easily find the vacancy and point defects." You mean like this for NIST 2000 SRM?
https://www.researchgate.net/post/What_is_the_best_way_to_interpret_REAL_TIME_3D_X_Y_Omega_2Theta_reciprocal_space_relative_intensity_data_from_HRXRD_rocking_curve_analyses
BTW how do you deduce these, the vacancy and point defects, from the reciprocal space parameters (Omega, 2-Theta, Phi & Chi Scans). Please post some references when convenient.
EDP & SEM are only sensitive to defects terminating at the sampling surface. Line-defects just as most other lattice distortions are 3D in nature. I'll post some comparisons soon.
Vijayakumar! What materials systems are of interest to you?
https://www.researchgate.net/post/What_is_the_best_way_to_interpret_REAL_TIME_3D_X_Y_Omega_2Theta_reciprocal_space_relative_intensity_data_from_HRXRD_rocking_curve_analyses
Thank you sir and we are growing good quality single crystals for mid-IR nonlinear optical applications (LiInSe2, LiInS2, AgGaInSe2, AgGaSe2, AgGaS2, GaInSe, GaInSSe, CdIn2Se4, GaGa2Se4, ZnIn2Se4 and CdInGaSe4), HRXRD characterization was done with help of Dr. G. Bhagavannarayana, Scientist and Head, NPL, Delhi.
What growth techniques for "(LiInSe2, LiInS2, AgGaInSe2, AgGaSe2, AgGaS2, GaInSe, GaInSSe, CdIn2Se4, GaGa2Se4, ZnIn2Se4 and CdInGaSe4)"?
What is the end-use of such materials systems?
"HRXRD characterization was done with help of Dr. G. Bhagavannarayana, Scientist and Head, NPL, Delhi." Does this mean you don't have enough expertise and information with this technique or you didn't have control of the experimental parameters and configuration details?
Bridgman technique has used to Grow crystals and these single crystal has potential application for frequency conversion in mid-IR region and optical parametric oscillators.
i don't have enough expertise. we grow single crystals and handed over to Dr. G. Bhagavannarayana, He give the results. from these result we interpret.
Usually SEM only provide information about Topography and Morphology of the film or sample.
For the Information you are seeking, Cathodo-Luminescence (CL) (an attachment to SEM), TEM etc can help you with.
Point defects (0-Dimention)- Vacancy, interstitial : Difficult to directly observed, usually their presence can be confirmed by their effect on physical and chemical properties (luminescence, carrier mobilities etc. ) of the material
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Line Defect (1-Dimention): TEM (destructive technique) gives direct evidence of the both type of defect but for that sample preparation is bit challenging. Another technique is X-ray topography( non destructive technique).
Thank you Dr.Jitendra Nuwad,
can we find the point defects from EDS analysis sir?
because composition of the materials gives the information about the stiochiometry.
from stiochiometry we easily conclude the nature of point defects.
Answer is NO,
There could be several types of point defect (missing element, foreign element in interstitial or lattice site etc), how you are going to represent in one stiochiometry.
EDS only tells about the bulk elemental composition of the material. EDS never tells about the material, it only tell about the element present in it. we only conclude that it could be that material. For Confirming the material there are other techniques available (Raman. XRD etc) .
Eg. diamond and graphite both are allotrope of C. Now EDS will only tell about element C presence. Now there could be several C element missing within the structure (point defects) or there could be other element present (N, B etc) as an impurity. Now EDS will only tell presence of C, N, B what you can tell from it.
To distinguishing these allotrope you have to analyze them by Raman spectroscopy (or XRD etc), both gives distinct Raman signature and to know about defects related to N, B, Photo luminescence may help.
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