Development of a laboratory system hard X-ray photoelectron spectroscopy and its applications

Highlights: •High Energy Angle Resolved Photoelectron spectroscopy system for laboratory use (HEARP Lab) with Cr Kα (5.4 keV) excitation was developed. •Basic performance of HEARP Lab has been estimated in comparison with that of typical beamline HXPES system. •Various applications including bulk valence band spectroscopy and buried layer analysis exemplify practical usefulness of HEARP Lab. •New methods including electric field application, high pressure photoelectron spectroscopy using environmental cell are introduced. •Several possible future developments are described. -- Abstract: Development of a laboratory hard X-ray photoelectron spectrometer using excitations by monochromatic Cr Kα X-rays of 5.4 keV and a high energy analyzer with a wide acceptance angle resolved objective lens is introduced. Wide applicability of the system as a powerful tool for the investigations of electronic and chemical states of materials are demonstrated by various examples including bulk sensitive valence band and core level spectroscopy, overlayer thickness determination by photoelectron take off angle dependence measurements, buried layer analysis, bulk sensitive photoelectron diffraction to determine surface polarity of compound single and poly crystalline films, interface state spectroscopy in MOS structures by applying voltage bias, and environmental cell for high pressure photoelectron spectroscopy. These results evidently show the laboratory HXPES system is going to be indispensable in wide varieties of targets. It also opens up opportunities of the analysis of materials which are not accessible to beamlines due to limitations by safety control regulation and avoidance of risks to the beamlines