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Mapping hidden space-charge distributions across crystalline metal oxide/group IV semiconductor interfaces

DOI: 10.1103/PhysRevMaterials.6.015002 DOI Help

Authors: S. A. Chambers (Pacific Northwest National Laboratory) , M. Chrysler (University of Texas-Arlington) , J. H. Ngai (University of Texas-Arlington) , T.-L. Lee (Diamond Light Source) , J. Gabel (Diamond Light Source) , B. E. Matthews (Pacific Northwest National Laboratory) , S. R. Spurgeon (Pacific Northwest National Laboratory) , M. E. Bowden (Pacific Northwest National Laboratory) , Z. Zhu (Pacific Northwest National Laboratory) , P. V. Sushko (Pacific Northwest National Laboratory)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Review Materials , VOL 6

State: Published (Approved)
Published: January 2022
Diamond Proposal Number(s): 25582

Abstract: The electronic structures of semiconducting heterojunctions are critically dependent on composition including the presence and concentrations of dopants, both intended and unintended. Dopant profiles in the interfacial region can have major effects on band energies which in turn drive transport properties. Here we use core-level photoelectron line shapes excited with hard x rays to extract information about electric fields resulting from internal charge transfer in epitaxial La 0.03 Sr 0.97 Zr x Ti 1 – x O 3 / Ge ( 001 ) ( 0.1 ≤ x ≤ 0.7 ) heterostructures. Experiments were carried out for heterojunctions involving both n - and p -type Ge substrates. These heterojunctions were not amenable to electronic characterization of all regions by transport measurements because the doped substrates act as electrical shunts, precluding probing the more resistive films and masking interface conductivity. However, the core-level line shapes were found to be a rich source of information on built-in potentials that exist throughout the heterostructure, and yielded valuable insight into the impact of band bending on band alignment at the buried interfaces. The electronic effects expected for Ge with uniform n - and p -type doping are eclipsed by those of unintended oxygen dopants in the Ge near the interface. This study illustrates the power of hard x-ray photoemission spectroscopy and related modeling to determine electronic structure in material systems for which insight from traditional transport measurements is limited.

Journal Keywords: Density of states; Electrical conductivity; Electronic structure; Growth; Localization; Percolation

Diamond Keywords: Semiconductors

Subject Areas: Materials, Physics

Instruments: I09-Surface and Interface Structural Analysis

Added On: 25/01/2022 09:32

Discipline Tags:

Surfaces Physics Hard condensed matter - structures Materials Science interfaces and thin films

Technical Tags:

Spectroscopy X-ray Photoelectron Spectroscopy (XPS) Hard X-ray Photoelectron Spectroscopy (HAXPES)