Comparative Study of Erbium Doped KDP Single Crystals Grown by Different Techniques

Erbium doped potassium dihydrogen Orthophosphate (KDP) single crystals were grown by different techniques – SR method, Seed Rotation and Slow Evaporation with the vision to improve the properties of the crystal. The objective of this study is to show how the dopant Erbium influences the growth, morphology and characteristics of KDP crystal. The crystal size grown by SR method on unidirectional {101} pyramidal face was around 150 mm in length and 16 mm in diameter. The Chemical composition of the grown crystals is confirmed by EDAX Analysis. The grown crystals are subjected to PXRD analysis using XrdwinPD 4-dectris computer based diffractometer with a characteristic Cu Kα (1.540598) radiations from 100 to 600 at a scan rate of 100/min, confirm the crystalline nature and shifts in peak positions due to doping is observed. Using Scherer's equation crstallite size has been calculated and the crystallite size is around 44 nm. Solubility of crystals grown by slow evaporation technique is determined using water as a solvent. The solubility curve shows that that Erbium doped KDP crystals has higher solubility than the pure KDP. The SHG efficiency is determined by Kurtz powder technique. It is found that relative SHG conversion efficiency of crystal grown by SR method is greater compared to other techniques. Optical transmission spectra are recorded for the crystals in the wavelength region 200 to 1100nm using Perkin-Elmer Lambda 35 UV-Vis spectrophotometer. It is found that percentage transmission of crystals grown by SR method is more as compared to other techniques. The electronic band transitions is studied from the plot of (αhv)2 versus photon energy (hv) and the band gap energy has been calculated. The addition of Erbium improves the quality and transparency of crystals, which shows the suitability of the ingot for optical applications.