High-resolution Scanning Transmission EBIC Analysis of Misfit Dislocations at Perovskite pn-Heterojunctions

T Meyer,J Lindner,B Kressdorf,M Seibt,V Roddatis,C Jooss,P Peretzki

doi:10.1088/1742-6596/1190/1/012009

T Meyer, J Lindner + Show 5 more

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https://doi.org/10.1088/1742-6596/1190/1/012009

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Abstract

Fundamental losses of photovoltaic energy conversion are transmission of sub band gap photons and thermalisation which are the underlying physics of the Shockley-Queisser limit defining maximum conversion efficiency of single-junction solar cells. Strongly correlated materials such as perovskites are promising candidates to exceed this limit by exploiting (i) long wavelength light absorption and (ii) the existence of long-living intraband excitations indicating that harvesting hot excess carriers might be feasible in such systems. In this work, we study pn-heterojunctions produced from Pr1-xCaxMnO3 on SrTi1-yNbyO3 by means of microscopic techniques. Such systems exhibit relevant quantities such as space charge layer width, screening lengths and excess carrier diffusion lengths in the 1-10 nm range which makes the use of standard methods such as electron beam induced current a challenging task. We report scanning transmission electron beam induced current experiments of misfit dislocations at the heterojunction. The dislocation-induced reduction of the charge collection is studied with nanometer spatial resolution. Effects of surface recombination and the heterojunction electric field are discussed.

Highlights

Transition metal oxide perovskites, in particular manganites, became popular in the 1950s due to their extraordinary magnetic properties [1]
Besides the advantageous characteristics for photovoltaic applications mentioned above, due to typically high doping levels and the low mobility of polaronic charge carriers, important physical properties of the resulting PCMO-STNO heterojunction such as the space charge region width as well as the screening and excess carrier diffusion lengths are in the 1-10 nm range [17] demanding for high-resolution technique to investigate the fundamental electric transport phenomena
Summary and Conclusion We have reported an experimental setup achieving a resolution of at least a few nanometers by means of scanning transmission Electron beam induced current (EBIC) (STEBIC) investigations offering the possibility to map the recombination and transport behaviour of transition metal oxide perovskites with relevant physical quantities in the 1-10 nm range

Summary

Introduction

Transition metal oxide perovskites, in particular manganites, became popular in the 1950s due to their extraordinary magnetic properties [1]. We report scanning transmission electron beam induced current experiments of misfit dislocations at the heterojunction.

Results

Conclusion