ZnS:ErF3 alternating current thin film electroluminescent (ACTFEL) devices are fabricated by rf plasma magnetron sputtering. In a full factorial design-of-experiment study, increasing deposition temperature, duty cycle on the doped target, and sputter gas pressure all result in increases in the 1.55 mu m near infrared (NIR) electroluminescence (EL) irradiance at 20 V above threshold (B-20). An increase in the EL threshold voltage (V-th) upon increasing the duty cycle of the undoped target is also reported. Postdeposition annealing of ACTFEL devices at 425 degrees C for 1 h improves the NIR EL irradiance by decreasing the F concentrations. in the ZnS:Er films. The origins of these effects are discussed in terms of negative ion resputtering, surface mobility of sputtered species, crystallinity, and the effects of atomic concentration on the EL and radiative relaxation processes. A maximum irradiance, B-20, of 147 mu W/cm(2) is measured for the 1.55 mu m NIR EL peak from ZnS:Er ACTFEL devices produced using a deposition temperature of 150 degrees C, a duty cycle of 75%, an argon sputtering gas pressure of 24 mTorr, and postdeposition annealing at 425 degrees C for 1 h in nitrogen. (c) 2007 American Vacuum Society.