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

Silicon microplasma devices with square trench cathode cavities having cross sections of (10μm)2 or (30μm)2 and a depth of 200μm have been fabricated and operated successfully in the rare gases and Xe∕O2 mixtures at pressures (300K) up to 1100Torr. The (10μm)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 10μm square devices is observed for pd≃0.9Torrcm (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 (∼510–560nm) is observed in mixtures of Xe(300–700Torr) and O2(1–10mTorr).