Advanced Physical Research

This study presents a detailed study of the pressure-dependent charge transport, electrical and optical properties of a microplasma electronic device based on a high-resistivity GaAs:Cr photocathode in a range of pressure from 60 to 600 Torr within a micro-scale gap of d_g = 45 µm, setting new operational limits for microplasmas in Xe environments. Current–voltage measurements reveal a stable transition to an abnormal glow discharge and the absence of filamentation up to atmospheric pressure. The experimental Paschen curves determine a minimum breakdown voltage of 230 V and an effective secondary emission coefficient γ = 0.01, providing a quantitative baseline for semiconductor-plasma interfaces. The optical performance is characterised by a non-monotonic pressure dependence with an optimal visible Xe plasma emission intensity at 304 Torr induced by the pressure-induced redistribution of the excitation rates and modification of the effective electron energy distribution, alongside VUV excimer quenching. High current operation results in a selective spectral blinding effect with a 40% reduction of the visible quantum efficiency, decreasing the sensitivity from 0.24 to 0.10 in the 462-467 nm diagnostic window. This degradation is due to preferential As sputtering and resonant surface ageing, quantitatively confirmed by fractal dimension analysis of the plasma-induced micro-pitting and morphological non-uniformities, which are directly related to the formation of localised erosion channels and morphological surface irregularities.