2024-01-24 パシフィック・ノースウェスト国立研究所(PNNL)
◆通常のフォトエレクトロン分光法では検出が難しい低濃度のドーパントに対し、この手法を用いてSTO/Si材料の表面での酸素欠損による電子状態を初めて観測。これにより、電子捕捉が材料の電気伝導に与える影響を理解する手がかりが得られました。
＜関連情報＞
- https://www.pnnl.gov/publications/studying-scarce-electrons
- https://journals.aps.org/prmaterials/abstract/10.1103/PhysRevMaterials.8.014602
n-SrTiO3-δ/i-Si(001)ヘテロ接合の表面近傍のギャップ状態の電子特性を高感度でプロービング Probing the electronic properties of gap states near the surface of n−SrTiO3−δ/i−Si(001) heterojunctions with high sensitivity
S. A. Chambers, Z. H. Lim, J. H. Ngai, D. Biswas, and T.-L. Lee
Physical Review Materials Published 19 January 2024
DOI:https://doi.org/10.1103/PhysRevMaterials.8.014602
ABSTRACT
We have measured soft x-ray resonant photoemission for the n−SrTiO3−δ/i−Si(001) (δ=∼0.0003) hybrid semiconductor heterojunction with the goal of probing occupied electronic states in the band gap near the surface. By utilizing both swept energy, angle-integrated and fixed-energy, and angle-resolved spectroscopies, we identify the atomic and orbital character of the in-gap state as well as the different electronic phases that contribute to it. Specifically, we isolate the state associated with trapped charge on the n−SrTiO3−δ surface that causes surface depletion from the localized gap state resulting from electron correlation effects in the complex oxide. Using an x-ray energy close to select dipole allowed TiL3→3d x-ray absorption resonances results in a 40-fold increase in sensitivity. This feature makes photoemission possible when probing electrons from dopants at concentrations as low as a few hundredths of a percent.
