Direct observation of bi-alkali antimonide photocathodes growth via in operando x-ray diffraction studies

M Ruiz-Osés,J Wong,K Attenkofer,J Smedley,I Ben-Zvi,T Rao,H Padmore,S Schubert,J Xie,E Muller,X Liang,T Vecchione

doi:10.1063/1.4902544

Abstract

Alkali antimonides have a long history as visible-light-sensitive photocathodes. This work focuses on the process of fabrication of the bi-alkali photocathodes, K2CsSb. In-situ synchrotron x-ray diffraction and photoresponse measurements were used to monitor phase evolution during sequential photocathode growth mode on Si(100) substrates. The amorphous-to-crystalline transition for the initial antimony layer was observed at a film thickness of 40 Å . The antimony crystalline structure dissolved upon potassium deposition, eventually recrystallizing upon further deposition into K-Sb crystalline modifications. This transition, as well as the conversion of potassium antimonide to K2CsSb upon cesium deposition, is correlated with changes in the quantum efficiency.

Highlights

Alkali antimonides have a long history as visible-light-sensitive photocathodes
The electron beam physics community has identified photocathodes as a key area of research needed to meet the challenges of generation light sources, where in particular, electron beams with very high repetition rate and low emittance will be required.[1,2]
We present results from a new tool for production and analysis of accelerator photocathodes. This device permits true in situ x-ray studies of alkali antimonide cathodes during growth, including x-ray diffraction (XRD), x-ray reflectivity (XRR), and grazing Incidence Small Angle X-ray Scattering (GISAXS)

Summary

Introduction

Alkali antimonides have a long history as visible-light-sensitive photocathodes. This work focuses on the process of fabrication of the bi-alkali photocathodes, K2CsSb. Direct observation of bi-alkali antimonide photocathodes growth via in operando xray diffraction studies

Results

Conclusion