Functional materials for information and energy technology: Insights by photoelectron spectroscopy

Abstract

The evolution of both information and energy technology is intimately connected to complex condensed matter systems, the properties of which are determined by electronic and chemical interactions and processes on a broad range of length and time scales. Dedicated photoelectron spectroscopy and spectromicroscopy experiments can provide important insights. We discuss some recent methodological developments with application to relevant questions in spintronics, and towards in-operando studies of resistive switching and electrochemical processes.

Chemical Stability of IrO2 Top Electrodes in Ferroelectric Hf0.5Zr0.5O2‐Based Metal–Insulator–Metal Structures: The Impact of Annealing Gas

“…The data allow us to conclude on the chemical properties and possible interactions of the HZO 2 layer and the top electrode interface. [13] Core-level spectra of Hf, Zr, Ir, and O were recorded at a photon energy of 6 keV. HAXPES, thereby, provides the large information depth required to probe the entire capacitor stack; [15,30] even signals from the IrO 2 bottom electrode could be detected.…”

“…Hard X-ray photoelectron spectroscopy (HAXPES) is used as an element-and depth-sensitive characterization technique. [13][14][15] Its information depth enables an investigation of the entire top electrode and the underlying HZO. In the way, we collect clear pictures of the chemical modifications of IrO 2 electrodes due to the RTA of IrO 2 /HZO/IrO 2 MIM structures.…”

Impact of vacancies and impurities on ferroelectricity in PVD- and ALD-grown HfO2 films

“…[4][5][6] Here, we present a comparative study of both ALD-and PVD-grown HfO 2 thin films interfaced with TiN bottom/top electrodes (BE/TEs) integrated into TiN/HfO 2 /TiN capacitors. We apply hard x-ray photoelectron spectroscopy (HAXPES) as an equally depth-sensitive and element-specific chemical characterization technique, 7,8 which allows us to gain a comprehensive picture of the chemical state of the HfO 2 layers. In our analysis, we focus, in particular, on identifying spectral signatures of oxygen vacancies and nitrogen/carbon impurities.…”

Hard x-ray photoelectron spectroscopy: a snapshot of the state-of-the-art in 2020

“…Whilst soft X-ray based ambient pressure systems are well established in both laboratories and at synchrotrons, the number of hard X-ray systems is small. [74,360,[368][369][370] Development of laboratory-based AP-HAXPES instruments started in the early 2010s by Kobayashi et al [74] Their system consisted of a monochromatic ULVAC PHI Cr Kα X-ray source and a VG Scienta R4000 analyser. It was able to reach a maximum pressure of 10 mbar through the use of environmental cells.…”