Metallizing vacuum boat

The organic deposition sources are made of a variety of materials including ceramics (e.g., boron nitride, aluminum oxide, and quartz) or metallic boats (e.g., tantalum or molybdenum). Deposition is carried out in high vacuum at a base pressure of around 10-7 torr. The vacuum conditions under which OLEDs are fabricated are extremely important [41] and evaporation rates, monitored using quartz oscillators, are typically in the range 0.01 0.5 nm/s in research and development tools. In manufacturing, higher rates or multiple sources may be used to reduce tact times. 

Heating coils or boats for vacuum metallizing (W and NS-W). Tungsten is an excellent material for evaporation sources. Coils (Fig. 7.13) and boats (Fig. 7.14) of different size and shape are used. The main application is to evaporate aluminum, but a variety of other metals and metal compounds can be evaporated too, as listed in Table 7.2. Evaporization is performed for metallizing different products such as reflector lamps, head lamps, television picture tubes, electronic components, plastic, etc. 

The Eulr2 alloy was prepared by direct combination of the metals. Europium chips, % in. on edge were placed in a V4 in.-diameter cavity of a die. Iridium metal powder, —325 mesh and 99.9% pure, was sprinkled over the rare earth element, and the mixture was compressed at 5000 psi. The compressed pellet was placed in a molybdenum boat, which then was transferred to a quartz sleeve, followed by insertion into a quartz reaction tube. The tube was attached to a glass vacuum line and evacuated. Argon was added to approximately 1 atm and the compressed pellet was heated to 900° C and held at the temperature for 14 hr. The product was air quenched to room temperature. The product was crushed in an agate ball mill, compressed into a pellet again, and reheated in the same manner as before. 

A successful laboratory method is reduction of the dioxide with an excess of calcium hydride in a molybdenum boat. The reaction is carried out at 900 °C in a vacuum or in an atmosphere of hydrogen5 (equation 1). Most of the hydrogen present can be removed by heating the metal in a vacuum at 1100 °C. 

A sample of cerium metal (approximately 15 g.), previously cleaned and weighed, is placed in a V-shaped tungsten boat. The boat is positioned inside a 26-mm.-o.d., heavy-wall, silica reaction tube, and a curved shield of tungsten foil is placed over the boat to prevent the possibility of silica flakes (formed by reaction with cerium vapor) from falling into the melt. The silica reaction tube is transferred anaerobically from the glove box and installed on the vacuum and gas-handling system. 

Evaporation is a process in which the target metal is heated in a high-vacuum environment and deposited onto the substrate. There are two main ways to heat the target metal resistive heating, where a high current is passed through a boat or... 

Fig. 5.37. (a) I/V characteristics of typical MDMO-PPV/PCBM solar cells with a LiF/A1 electrode of various LiF thicknesses ( 3 A, 6 A, 12 A) compared to the performance of a MDMO-PPV/PCBM solar cell with a pristine A1 electrode ( ). (b) and (c) are box plots with the statistics of the FF and Voc from 6 separate solar cells. LiF or SiOx were thermally deposited at a rate of 1-2 A/min from a tungsten boat in a vacuum system with a base pressure of 10-4 Pa. We emphasize that, for thickness values of the order of 1 nm, LiF/SiOx does not form a continuous, fully covering layer, but instead consists of island clusters on the surface of the photoactive layer. Slow evaporation conditions are essential for more homogenous distribution of the LiF on the organic surface. The nominal thickness values given here represent an average value across the surface of the substrate. The metal electrode (either aluminum or gold) was thermally deposited with a thickness of 80 nm... 

FIG. 10.5. (a) A glass moisture trap containing a boat for phosphoms pentoxide. (b) A metal moisture trap in section, showing the trays for phosphoms pentoxide. (c) Oil reservoir, fitted to tlie vacuum connection on a rotary oil pump. Tlie two-way stopcock is opened to tlie atmosphere when the pump is stopped. 

Flash evaporation is another techniqne for the deposition of films whose constituents have different vapor pressures. Small quantities of the constituents in the desired ratio are continuously dropped at a predetermined rate from a vibration feeder into a sufficiently heated crucible or boat so that they are evaporated instantly. The temperature must be sufficiently high to evaporate the less volatile material. Figure 2.3 shows the flash-evaporation apparatus used to grow the different layers that compose a microbattery metallic contacts, cathode, electrolyte, lithium anode deposited under vacuum of 10-100 mPa pressure. This system has two vacuum chambers. Vacuum chamber A is devoted to evaporation of In-Se films while lithium and glass films are formed in chamber B. Two interlock mechanisms are used the first one transfers the grown In-Se film to the chamber B and the second interlock system is ntilized to carry lithium pieces from an inert-gas glove box to the evaporation boat. 

The three solid phase compounds were mixed, pelleted, dried and heated in an alumina boat in a quartz tube attached to an all-metal vacuum system and the resultant C02(g) pressures measured manometrically at ten temperatures between 952 and 1098 K. Equilibration times were 200-400 h and attaimnent of equilibrium was checked by removal of some C02(g) and allowing the equilibrium to be attained again. 

Less volatile metals can also be distilled, in smaller quantities, in a timgsten boat heated to Fig. 77. Vacuum... 

The commercial metal is crushed in a steel mortar and screened through a 100-mesh ftier inch) sieve the powder is placed in a corundum boat, which is heated in a porcelain tube in a dry NH3 stream at 850°C for three hours. The reaction product is then pulverized in an agate mortar and heated in the NH3 stream at 1000°C this procedure is repeated three times. The product so obtained usually contains only 94-95% BeaNg. A purer product might be obtained by the use of metal stilled in high vacuum and by careful manipulation. 

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