TECHNOLOGY FOR CRYSTAL GROWTH
1.-CZOCHRALSKI, WITH DIAMETER CONTROL The Czochralski furnace equipment developed in our laboratory consist in a compact set-up to grow a great variety of single crystals, like Lithium Niobate, pure and doped, bulk Periodic Poled Lithium Niobate, oxides, alkaly halides, fluorides (with control atmosphere) and others materials. All the equipment is controlled by a personal computer, which monitors all the growth process. The set-up contains a typical PID program and an innovative fuzzy-logic control program developed in our lab. Using our experience in the materials field for more than 20 years.All the phases of the growth process can be controlled such as the shoulder formation,the diameter of the crystal, the growth parameters, etc. The furnace works up to 1400ºC. With some modificationsis possible to use the equipment like a Liquid Phase Epitaxy furnace. The Crystal Growth Lab. is equiped with six Czochralkski with control diameter
2.-VERTICAL GRADIENT FREEZE (VGF) TECHNIQUE FOR THE GROWTH OF HIGH QUALITY CDZNTE (CZT CRYSTALS) For the growth of high quality CZT single crystals, we have designed and fabricated the five zone VGF furnace. The total equipment was controlled by home made software and we can able to maintain the precise temperature for the above said growth. In this technique, we are changing only the temperature profile and there is no translation of the ampoule (ampoule is stationary).
3.-OSCILLATORY BRIDGMAN The Oscilallatory Bridgman equipment consist in a double resistance furnace which can oscillate alternatively till a maximum of 90º in order to get a good mixture of all the chemicals located in the growth ampoule. Prior of the growth process, the ampoule oscillate during a limit time at a programmed oscillation speed. After this process, the ampoule is lowered down at a growth speed from 0.3 till 10 mm/h. The equipment is totally computerized. The Crystal Growth Lab. is equiped with two oscillatory Bridgman apparatus. In this equipment hasbeen grown semiconductor materials like InSb, GaSb and InGaSb. The maximum temperature reached by these equipments is 1000º C.
4.-FLUX EQUIPMENT The flux equipment is a totally isolated box with three Temperature Controllers and with a set of 8 thermocouples to monitor the temperature in differents places. The furnace is made of Kanthal resistance with a maximum temperature of work of 1100 ºC. The equipment is prepared for growing materials using the flux method.
5.-POLISHING MACHINES The polishing machines are the most simple and cheapest version of a polishing machine,for any material used in optical applications. Lapping and polishing processes can be easilydone. The polishing machine is consecuence of our experience in the preparation of materials from the past 20 years.
6.-Closed Space Sublimation (CSS) A vapour phase technique mainly used to growth thin films of II-VI compounds such as CdTe and CdS. This technique IS A key techniques on photovoltaics field. 7.- Spray Pyrolysis By MEANS of pulverization of solvents with suitable ions, a chemical reaction is obtained over a hot substrate. THE RESULT IS A SMOOTH and homogeneous films. Mainly used for depositing Transparent Conducting Oxides SUCH as ITO, SnO2 and ZnO2 8.-COREMA COntacless Resistivity Mapping: automatic equipment for measuring the volume resistivity of samples with a range of 10E5-10E10 ohm.cm 9.-VGF II 5 zone VGF Furnace 50mm diametre 10.-Bridgman III Bridgeman design to provide for stationary ampoule with travelling furnace Furnace rotation to 60deg. included for homogenization Up to 65mm capacity Furnace temperature profile to be callibrated using a Zirconium Phosphate ceramic boule (identical thermal conductivity to CdZnTe)