SurfaceScience21 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 46: Poster Session IV: Semiconductor substrates II
O 46.4: Poster
Dienstag, 2. März 2021, 13:30–15:30, P
Caesium deposition on GaN to obtain a photocathode for particle accelerators — •Jana Schaber1,2, Rong Xiang1, Jochen Teichert1, and André Arnold1 — 1Department of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany — 2Department of Physical Chemistry, Technical University Dresden, Dresden, Germany
Negative electron affinity (NEA) GaAs- and GaN-based photocathodes are used in modern night vison detectors and light emitting diodes. GaAs semiconductors are already used as electron sources in particle accelerators and well- studied. Like GaAs, GaN belongs to the III-V semiconductor group with similar properties. It is assumed that GaN, like GaAs, shows enormous potential as a novel electron source for particle accelerators.
P-type GaN on different substrate material (sapphire, silicon, copper or SiC) is activated by a thin layer of caesium and illuminated by ultra-violet (UV) light at the same time. As a consequence of negative electron affinity (NEA) and photoeffect, the generated photoelectrons enter into vacuum and are collected by a copper ring anode. The resulting photocurrent is detected during the whole activation process and stopped when a maximum photocurrent is reached. By a comparison of differences in substrate material, chemical pre-cleaning, thermal heat treatment and activation parameters (e.g. caesium-flux), the photocurrent, quantum efficiency and the re-activation of the photocathode is studied. Additionally the GaN samples are examined by AFM, SEM and EDX.