The Crystal Growth Centre, Anna University has expertise on the Crystal growth and development of

• Semiconductor wafers of Ge, GaAs, InP, InSb, CdTe and other III-V materials.
• Non-linear optical crystals of KTP, KDP and related materials, Borate family of crystals, Urea and related materials, Thio-Urea complexes, other Semi-organic and organic crystals.
• Laser crystals of double Tungstates, doped sapphires and others
• Ferroelectric materials of TGS, KDP, BaTiO3 and related materials, etc.
• Piezoelectric crystals of lead molybdate, PMN-PT, PZN-PT and others
• Bio-materials of Calcium phosphates and related materials, Cholesterol and related materials, oxalates and tartrates, etc.
• Heterostructures of GaN, GaAs and other III-V materials.
• Device structures of light emitting diodes (LEDs) and high electron mobility transistors (HEMTs)

The Centre has taken up following projects for various sponsorers.

• Bulk Crystal Growth of Germanium, Gallium Arsenide, Indium Phosphide
• Development of Crystal Pullers
• Development of Biosensors
• Growth of thin films of Indium Oxide, Indium Tin Oxide, AlQ3 based Organic LED structures, High Purity Metals and Alloys, Gallium Nitride, Zinc Oxide, etc,

The technical support and expertise can be extended to the following Industries;

Semiconductor based Industries through transfer of technology for the development of wafers.

• Laser and Optical materials based Industries through supply of raw materials.

• Photonic industries through the technology transfer of LED and other components development.

• Energy and Environment based ventures for the production of solar cells and pollution free energy resource.

• Bio-Industries, through the technology transfer of bio-compatible material development and characterization of materials.

• Metal extraction and purification industries
• High Purity Chemicals production companies
• Nano science and technology based industries
• Thin Film coating industries
• Biosensors

Professor

22203569/ marsjk@annauniv.edu

Professor

22203572/ rdhanasekaran@annauniv.edu

Asst. Professor

22203571/ rjvel@annauniv.edu

Asst. Professor

22203579/ baskar@annauniv.edu

Asst. Professor

22203576/ babu@annauniv.edu

Asst. Professor

22203577/ kalkura@annauniv.edu

Growth and characterisation of Gallium Nitride and Alloy systems to
fabricate UV detectors”

Synthesis, growth and characterization on Nanostructured
optoelectronic materials.

Radiation detectors and irradiation studies on semiconductor device structures

Growth and characterisation..alloys application

Development of NLO devices from stoichiometric Lithium Niobate Single Crystals

Nanostructure formation on metal / semiconductor growth and characterization of DMS materials for spintronic applications

Effect of irradiation on hydroxyapatite and their biological performance

Heavy iron irradiation effects on colossal magnetoresistance (CMR)
single crystals

Growth and Characterisation of Borate based single crystals and
fabrication of SHG elements

Stoichiometric lithium niobate single crystals for advances in
non-linear devices

Indo-Italian joint research project-” Crystal growth ……….spintronics”

Semiconductor Nanostructures

GaN and nitride alloy systems for nanoelectronics

Synthesis and Development of Nano-Crystalline semiconductor materials for advanced Application

Development of laser elements of double tungstates for diodepumped solid state laser applications

Growth and characterization of bimetallic Thiocyanate Crystals for Frequency Conversion devices

EU-ASIA LINK Programme

Growth and Characterization of Bimetallic Thiocyanate Crystals for Frequency Conversion Device

Investigations on the synthesis of nanocrystalline calcium phosphates to prepare bone and dental replacement materials and drug delivery systems

Brief Write up of Most Successful Research Projects:

Growth and Characterisation of Borate based Single Crystals and Fabrication of SHG Elements
Borate crystals are used as high power UV Lasers in the field of medical science, material science, telecommunications and data storage etc. Hence, NLO borate crystals are gaining more importance. Some of the borate crystals like Potassium Aluminium Borate (KAB), Yttrium Calcium Oxy Borate (YCOB) have very good Non-Linear Optical properties when compared with other NLO borate crystals.
Procedure for synthesis and growth of high quality borate crystals like KAB and YCOB optimized. The structural, optical and spectroscopic data of the grown crystals documented .Consulting can be taken up for the growth and synthesis of hereby laser crystals and SHG elements.

High energy irradiation studies on II-VI nanocrystalline thin films and I- III- VI2 Chalcopyrites
The II – VI nanocrystalline thin films and I-III-VI2 chalcopyrite’s were synthesized. The optimized procedure for the development of the films were studied their stability for the high energy irradiation are identified. The similarity of the process and the materials for device has been documented.

Nanostructure formation on Metal / Semiconductors, Growth and Characterisation of DMS Materials using Swift Heavy Ion Beams
Gallium nitride exhibit wurzite crystal structure and has a direct band gap value of 3.4 eV. GaN is mainly used in high temperature optoelectronic devices. Swift heavy ion irradiation (SHI) in GaN is a subject of current research interest and is of technological importance. SHI creates point defects along its trajectory in a solid; leading to tracks because of the energy of point defect creation is significantly less than the average binding energy of target electrons. These defects are responsible to modify the physical properties of the materials. The samples used in this study are 3 µm thick n-GaN epilayers grown by Metal Organic Chemical Vapour Deposition technique on Sapphire substrates. The mobility and carrier concentration of grown GaN layer are 600 cm2 V.s and 6 E 16 cm-3. 100 MeV Ni 7+ ions of fluence 1E12, 5E12, 1E13 and 5E13 ions cm-2 irradiated at room temperature and 77K using 15 UD that Pelletron Accelerator at Inter University Accelerator Centre. XRD measurements were carried out on irradiated samples using D8 Brucker AXS X-ray diffractometer with Cu Ka source. XRD spectrum of pristine GaN sample exhibits c-plane texture. After Ni iond irradiation it was found that the GaN and sapphire substrate XRD peak intensity decreased. The FWHM of irradiated GaN increases with increasing fluence. AFM measurements indicate nanotrack formation after Ni ion irradiation at low temperature.

GaN and Nitride alloy systems for Nanoelectronics
Gallium Nitride (GaN) nanocrystals have been grown on the tip of aligned carbon nanotube (CNTs) substrate by Chemical vapour transport method. It was found that GaN nanocrystals were formed on the tip and outermost shells of CNT bundles in the form of nanorods. X-ray diffraction pattern shows that the GaN nano crystals are of wurtzite structure. Scanning electron microscopy (SEM) images show the nano crystals ranging from 10 to 100 nm have been realized under different experimental conditions exhibiting different shapes. Heterojunctions between CNTs and GaN nanocrystals, depending on their unique property, can be utilized for nanosized optical and optoelectronic devices. UV- optical absoroption spectrum show the band edge at 360 nm which is related to the bandgap energy of GaN.

Semiconductor Nanostructures
MOCVD facility towards the realization of Semiconductor Nanostructures. Was established Gallium Nitride (GaN) epilayers are continuously grown on both sapphire and silicon carbide substrates using chloride vapor phase epitaxy suitable for device fabrication

Stoichiometric Lithium Niobate single crystals for advanced non linear devices
Since there is always a need for the nonlinear devices for a plenty of applications, this project is dedicated for the growth of Stoichiometric Lithium Niobate single crystals which is well known for its higher nonlinearity. For the growth of such crystals, an induction furnace which is bought from Linn High Therm, Germany was interfaced with the Eurotherm Temperature Controller and the system was cooled using a compact chiller. The different parameters were resolved and growth processes are optimised for the growth of good quality Lithium Niobate single crystals. The crystals were grown using Platinum crucible. The grown crystals characterised for their suitability in laser and Non-Linear optical devices. Growth technology and the materials data were docmented.

Synthesis, Growth and Charcterisation on Nanostructured optoelectronic materials
Electron beam evaporation system for the development of thin film nanostructures of CdTe, ZnSe and CdZnSe2 was developed growth procedure for the template semiconductor nanostructure was optimized.

Growth and Characterization of Bimetallic Thiocyanate Crystals for Frequency Conversion Devices
Synthesis and growth of high quality bimetallic thiocyanate [Zinc cadmium thiocyanate (ZCTC), Cadmium mercury thiocyanate(CMTC),Manganese mercury thiocyanate (MMTC) and Zinc mercury thiocyanate (ZMTC)] single crystals were optimised for second order nonlinear optical (SONLO) applications.
The above mentioned crystals play a vital role in the generation of compact blue lasers. These are considered to be attractive for many applications such as, high-density optical data storage, medical diagnosis, photolithography, spectroscopy, under-water transmission, and colour displays, direct frequency up-conversion of near infrared semiconductor laser diodes (LDS) possibility of robust compact and reliable blue lasers.

Effect of irradiation on hydroxyapatite & their biological performance
Hydroxyapatite (HAp) is the main mineral constituent of bones and teeth. Bone contains carbonated-HAp crystals in the form of plates and needles, which are about 40–60 nm long, 20 nm wide, and 1.5–5 nm thick. Therefore from the point of view of biocompatibility, synthetically prepared HAp seems to be the most suitable ceramic material for hard tissue replacement implants. HAp ceramics does not exhibit any cytoxic effects. It shows excellent biocompatibility with hard tissues and also with skin and muscle tissues. Moreover, HAp can directly bond to the bone. Hydroxyapatite has a high affinity for natural tissue in situ and can be molded to fill spaces created by physical damage of bones and or teeth. It also has been an attractive material for chromatographic separation, catalysis and ion exchange apart from their use as bone and teeth implants. Implants for knee, hip and dental part replacement are becoming increasingly used in surgery. Surface treatment has been identified as a good candidate to modify the surface properties of the implant to significantly improve its osseointegration. The ion beam irradiation method enables modification of the chemistry of the HAp in a reproducible way so as to optimize the bone response to the implant and improve biointeraction for cell adhesion and proliferation, haemocompatibility and water absorption. Also irradiation of hydroxyapatite results in surface densification.
High energy oxygen ion irradiation has been used to modify the surface chemistry of the sol-gel derived microwave sintered HAp pellets. The irradiated surfaces showed unique bioactivity, forming spherical macroporous apatite layer which can enhance osteointegration and osteoconduction.
The experiments concluded SHI irradiation on HAp didn’t change its phase but reduced its particle size. Pits due to the bombardment of the oxygen ions could also be seen. Reduction in particle size and pore formation was observed in all the irradiated samples.These pores will allow growth of blood vessels, which aids biocompatibility. This is the first report of irradiation on pure HAp with high-energy ion and it showed excellent bioactivity and improvement in its surface properties.

Growth and Characterization of Alloys of InSb and InAs Epitaxial Layers for Infrared detector applications
InAs layers were grown on InAs and GaAs substrates by LPE in an ultrapure palladium diffused hydrogen ambient using a horizontal sliding graphite boat system. Grown layers were irradiated with 70MeV Si5+ ions the suitability of the layers for infrared detector application were evaluated.

Heavy ion irradiation effects on Colossal Magneto Resistance (CMR) Single Crystals
The divalent ion doped perovskite manganites La1-xDxMnO3; D=Ca, Sr, Ba, Pb, etc. have attracted a great deal of attention because of their potential applications, in magnetic sensors, switching devices, read/write heads and storage device etc. Perovskite manganites La1-xDxMnO3; D=Ca, Sr, Ba, Pb were prepared. The electrical and CMR values are determined.