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A technique used to determine the atomic and molecular structure of a crystal, in which the crystalline atoms cause a beam of incident X-rays to diffract into many specific directions.

Application of XRD
• XRD is a non-destructive technique
• XRD is most widely used for the identification of unknown crystalline materials
• To identify crystalline phases and orientation
• To determine structural properties
• To determine atomic arrangement

Results
Amorphous: a very broad humped peak
Crystalline: sharp peaks

Limitation
1. less effective in analyzing amorphous or non-crystalline materials because they lack a well-defined internal structure.
2. XRD requires a sufficient quantity of the material for analysis, making it less suitable for trace analysis.

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Definition : An optical measurement technique based on analyzing the change in the polarization state when a beam of polarized light was reflected from the surface or interfaces of coatings

Purpose : to extract the thickness, optical properties, and composition of the coatings.

How does it work?

1. light is passed through a polarizer

2. The beam then interacts with the sample and either reflects or transmits through it

3. The reflected/transmitted light is picked up by a detector that measures the changes in the polarization of the light

4. These changes are then compared to a model of the sample to infer information about its properties

Preparation to the sample

1. Samples are in the form of thin films with thickness between 1nm to 1000nm

2. The films should be transparent / semitransparent to allow light to pass through

3. Roughness should not be too high

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Model Name: JEOL JSM-IT300LV

Variable Pressure Scanning Electron Microscopy is a technique used to produce high-resolution images with a high depth of field. VPSEM differs from traditional SEM in that the instrument chamber is operated at higher pressures (~10 Pa to 3,000 Pa) which allows for imaging and analysis of insulating samples without the need to apply a conductive coating.

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AFM is a valuable technology for characterizing and fabricating microelectronic devices. It offers high-resolution imaging for examining surface topography and morphology at the nanoscale. AFM can assess material properties like roughness and mechanical characteristics, providing insights into device quality. It also enables the investigation of electrical properties using techniques like KPFM and C-AFM, which are essential for understanding device behavior and performance.

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Function:
Imaging surface at atomic level

Working principle:
The scanning tunneling microscope (STM) works by scanning a very sharp metal wire tip over a surface. By bringing the tip very close to the surface, and by applying an electrical voltage to the tip or sample, we can image the surface at an extremely small scale – down to resolving individual atoms.

Tunneling:
The starting point of the electron is either the tip or sample, depending on the setup of the instrument. The barrier is the gap (air, vacuum, liquid), and the second region is the other side, i.e. tip or sample, depending on the experimental setup. By monitoring the current through the gap, we have very good control of the tip-sample distance.

Procedure:
1. Close to sample
2. piezoelectric scanner tubes for fine control
3. Bias voltage is applied between the sample and the tip
4. Scanner is gradually elongated until the tip starts receiving the tunneling current