Microdischarge devices with 10 or 30 μm square silicon cathode cavities: Pd scaling and production of the XeO excimer

Silicon microplasma devices with square trench cathode cavities having cross sections of (10 μm) 2 or (30 μm) 2 and a depth of 200 μm have been fabricated and operated successfully in the rare gases and Xe O2 mixtures at pressures (300 K) up to 1100 Torr. The (10 μm) 2 structures exhibit electrical characteristics that contrast with the behavior of larger devices and may indicate the onset of the breakdown of pd scaling. Also, a distinct minimum in the ignition voltage of 10 μm square devices is observed for pd≃0.9 Torr cm (p and d are the Ne gas pressure and microcavity cross-sectional dimension, respectively). Strong emission on the 2 +1 →1 +1 transition of XeO in the green (~510-560 nm) is observed in mixtures of Xe (300-700 Torr) and O2 (1-10 mTorr).