The sputter system allowed as many as seven 1 x2 substrates and one bare glass

substrate of the same size to be processed simultaneously. The bare glass substrate was

used in each run to measure the film thickness by stylus profilometry so that 1 tm

thickness of phosphor film could be maintained. The substrates were preheated by a

carbon heater and rotated at 7 rpm by a stepping motor during deposition to enhance

uniformity. The load-lock chamber was pumped down to 10 mTorr by a wet rotary piston

roughing pump (Leybold Trivac D65B). The base pressure of the system was

approximately 10-6 Torr and it's achieved by a turbomolecular pump (Leybold Trubovac

450). The working pressure was raised to 20 mTorr by flowing argon, controlled by the

gas flow rate and a throttle valve, which is installed between the main chamber and

turbomolecular pump. There are also several gauges which are used to measure vacuum

pressure. The thermocouple gauges were used to measure the pressure of the load-lock

chamber, the ionization gauge was used to measure the base pressure of the main

chamber, and the capacitance manometer was used to monitor working gas pressure

during deposition.

 Performance of EL device is influenced by deposition conditions, including

substrate temperature, deposition time, concentration of doping elements, work pressure,

etc. Conditions for phosphor deposition were evaluated and optimized by measuring the

brightness at 40V above threshold of half-stack devices. In a separate study [49], it was

shown (Fig 3.1 and Fig 3.2) that for ErF3 and TmF3, the best processing conditions are as

shown in Table 3.1.