Plasma characterization of the gas-puff target source dedicated for soft X-ray microscopy using SiC detectors

Extreme ultraviolet (EUV) and soft X-ray (SXR) radiations have a wide range of scientifi c [1], biomedical [2], and industrial applications [3]. For these reasons, monitoring the radiation parameters on line, such as the energy, intensity, angular distribution and reproducibility becomes very important. Semiconductor detectors play an important role due to their high sensitivity, linearity and fast, subnanosecond response time. In particular, SiC photodiodes, having 3.2 eV energy band gap, are insensitive to the visible light wavelengths emitted from the plasma that generally constitute a pedestal for Si detectors. Moreover, these detectors having high robustness, very low dark current at room temperature and small response time, can be employed to monitor the EUV and SXR radiation emitted from laser-matter interactions. The 4H-SiC Schottky photodiodes working in the photovoltaic regime have high signal-to-noise ratio at room temperature. High sensitivity to the near UV radiations and SXR wavelength range is obtainable using interdigit contacts based on Ni2Si metallization strips. The contact geometry leaves the SiC active region directly exposed to the UV radiation and enables high absorption effi ciency even at short wavelengths. The low dopant concentration in the epitaxial layer on the top side of the structure allows to generate a narrow conductive channel (pinch-off) at the surface all around the adjacent Ni2Si stripes, already at very low negative voltages. Metals and semiconductors act as a p-n junction (Schottky), creating a depletion region that pinches off a conducting channel buried inside the semiconductor [4]. Plasma characterization of the gas-puff target source dedicated for soft X-ray microscopy using SiC detectors Alfi o Torrisi, Przemysław Wachulak, Lorenzo Torrisi, Andrzej Bartnik, Łukasz Węgrzyński, Henryk Fiedorowicz