Raman spectroscopy is a non-destructive chemical analysis technique which provides detailed information about chemical structure, phase and polymorphy, crystallinity and molecular interactions. A Raman spectrum shows the energy shift of the excitation light source (laser) because of inelastic scattering of the chemical bonds within the molecules. Chemical species consist of specific atoms and bonds, with certain vibrational modes, so each molecule possess characteristic Raman spectrum as a unique figure print of measured species.

The signature Raman peak for single crystal diamond is identified at 1332 cm -1 which is due to first order Raman shift, also the second and third order Raman shift can be observed at ~2700 cm cm -1  and ~3600 cm-1   depending on excitation source wavelength. With inclusion of any defects (impurities, vacancies and doping) leads to stress in the lattices with can quantify by Raman shift in the spectrum.

Photoluminescence integrated with Raman spectroscopy system is also  is a nondestructive analytical technique in which material is irradiate by photon energy source usually from a laser, and the resulting luminescence is recorded as a plot of emitted light intensity versus wavelength. It primarily determines electronics transitions in materials.

PL of diamond analyze atomic-scale features such as optical centers and optical defects within the diamond lattice which includes carbon, nitrogen, boron as substitution or as vacencies in the diamond lattice. It also identify presence of graphitic inclusions and metallic inclusions into diamond structure.

PL is an extremely sensitive tool for detecting deviations in atomic configurations and defects even at concentrations of less than ten in a billion (PPb) carbon atoms.

Uv-ViS-NIR quantify amount of light absorbs (transmitted) by  the material. This is done by measuring the intensity of light that passes through a sample with respect to the intensity of light through a reference sample or blank.

Diamond crystal structure contributes to its unique optical properties, to first order, diamond is transparent from its (indirect) electronic band gap (at 225 µm) to the microwave region. Colour in diamond comes from impurities, when the impurities are in sufficient concentration. For a defect-free diamond there is no absorption in the visible region, and it is therefore completely colourless. In reality, most diamonds are coloured, and so must absorb light in the visible region. This absorption is due to the presence of defects which can be identify using this technique.

It is an analytical method used to characterize the bonding structure of atoms based on the interaction of the IR radiation with material, and measures the frequencies of the radiation at which the substance absorbs and lead to the production of vibrations in molecules.

The diamond FTIR spectrum may be divided into three regions: three-phonon region (4000–2600 cm-1) for intrinsic diamond and B or H in diamond, two-phonon region (2600–1500 cm-1) for diamond and B in diamond and one-phonon region (1500–400 cm-1) for N or B impurity in diamond. In the 4000–1500 cm-1area some peaks appear which can be caused by the vibration of C‒C bonds of the diamond lattice. FTIR spectroscopy is a proven method to differentiate between authentic diamonds, to determine the type of a diamond and to determine the quality of diamond before and after HPHT treatment.

Fluorescence spectroscopy is a type of luminescence  which analyzes fluorescence in the sample. The sample is excited by a beam of light which results in emission of light of a lower energy (higher wavelength) resulting in an emission spectrum. The emission persists only as long as the stimulating radiation is continued.

Fluorescence spectrum of the natural-color diamonds has three categories—based on the peak wavelength and shape of the spectra (1) ~450 and ~490 nm, recorded mainly for pink, yellow, and fancy white diamonds; (2) ~525 nm, mainly for green yellow or yellow-green and brown diamonds; and (3) ~550 nm, mainly for orange, gray-green, and type Ia blue-gray or gray-blue diamonds.

The fluorescence spectroscopy can be used to separate colorless and near-colorless (D to J color grades) natural diamonds from laboratory grown diamonds and diamond simulants, detect multi-treated pink diamonds, and identify certain colored gemstones. Fluorescence spectrum may indicate the type of diamond and details about the HPHT treatment carried on diamond crystal.

Nano-Indentation : The mechanical properties of the diamond materials and GaN coating (SSMG development) such as hardness and Young’s modulus will be examine through the nanoindentation test method. The grains which are in the nano-level are difficult to measure through the conventional hardness test method. Hence in this method, three face Berkovich tips of the total included angle of 130.5° and the radius of curvature ~150 nm) indented on the surface of the sample to measure the hardness and young’s modulus of the samples.

Atomic Force Microscopy (AFM) is a high-resolution non-optical imaging technique for surface analysis. AFM allows accurate and non-destructive measurements of the topographical, electrical, magnetic, chemical, optical, mechanical, etc. properties of a sample surface with very high resolution in atomic regime. The instrument uses a cantilever with a sharp tip at the end to scan over the sample surface where attractive or repulsive forces between the tip and sample cause a deflection of the cantilever. The deflection is measured by a laser which is reflected off the cantilever into photodiodes. As one of the photodiodes collects more light, it creates an output signal that is processed and provides information about the vertical bending of the cantilever. This data is then sent to a scanner that controls the height of the probe as it moves across the surface. The variance in height applied by the scanner can then be used to produce a three-dimensional topographical representation of the sample

To examine surface morphology of LGD and HPHT treated diamond crystal to atomic levers are essential especially after polishing. The nanoscale grooves can be detected on the crystal surface according to the direction (soft and hard) and plane of crystal, also surface roughness can be quantified post polishing of the crystal with AFM.

Spectroscopic ellipsometry is a non-destructive, noncontact, and non-invasive optical technique which is based on the change in the polarization state of light as it is reflected obliquely from a thin film sample. Ellipsometry uses a model based approach to determine thin film, interface, and surface roughness thicknesses, as well as optical properties (refractive index n , and extinction coefficient k) for thin films ranging in thickness from a few Å to several tens of microns. Also, it can be performed either ex-situ or in-situ, in static or kinetic mode, for various application needs.

Optical properties (refractive index n , and extinction coefficient k) and thickness of CVD grown diamond films required to measure precisely. Change in refractive index indicate inclusion or impurities (colour centre) present in the diamond films which can be identified using Ellipsometry, and also the transparency (colourlessness) can be quantify with precision.

High resolution optical microscopes have higher resolution than conventional optical microscopes. For preliminary examination of as grown LGD and HPHT treated diamond crystal high resolution imaging is essential. The high-resolution microscope provides a tool to quality check the surface finishing of the diamond crystal pre and post polishing as well.

Laser cutting machines: The physical appearance of grown single crystal diamond from the seed substrates using MPCVD reactor for several days will shows the black coloured (non -diamond phases) region around the periphery of the grown crystal sides. To remove those black region, we need laser cutting machine which exactly coring the respective region from the grown single crystal diamond. Also, to separate the grown diamond crystal from seed substrate, we also need laser cutting machine to precisely cut the respective grown thickness.

Diamond polishing machine: The surface texture of the seed crystal is very important to achieve the gem quality single crystal diamond. Typically, the surface finish of the seed crystal will be around the value of Ra = ~ 5nm which is recommended for growing high quality crystals. But in actual, the grown crystal which will used as a seed substrate will be having a roughness of more than Ra= 5nm which we need to go for polishing route to bring down to a required Ra value of ~ 5 nm. Hence, we need dedicated polishing machine for super finishing the seed substrate effectively as per the recommended surface finish values.

Mask-less lithography: Understanding the electrical properties of MPCVD-grown diamond thin films is crucial for developing a recipe for producing high-quality diamond thin films. In addition, quantitative defect information can be extracted from electrical data and used to validate the optical properties of diamond films. Good metal contacts are required for electrical measurements, and lithography is the most effective technique for producing good electrical contacts. Mask-less lithography is a cutting-edge photolithography method that enables the direct transfer of patterns onto large wafers. In addition, the lithography tool would be beneficial for generating contacts and other patterns on solid state microwave generator (SSMG) chips, making it useful for SSMG development. Therefore, a mask-less lithography equipment is required to carry out the proposed project

Scanning electron microscope (SEM) uses a focused beam of high-energy electrons to generate a variety of signals at the surface of solid specimens. The signals that derive from electron-sample interactions reveal information about the sample including external morphology (texture), chemical composition, and crystalline structure and orientation of materials making up the sample..

To examine surface morphology of LGD and HPHT treated diamond crystal to sub- micron levers are essential. Post-polishing quality check of diamond crystal to submicron lever is essential, compact tabletop SEM system will help in determining diamond crystal finish.

Cathodo-lumiescense (CL) occurs when a diamond is expose to strong electron beam of electron. The energy of electron excites lattice defect and cause crystal to luminescence. It is use to identify CVD, as grown and HPHT treated diamonds.