Effects of varying the oxide composition on the terahertz emission of n-Si/CuxO heterostructures

Authors

  • Horace Andrew F. Husay National Institute of Physics, University of the Philippines Diliman
  • Arven I. Cafe Materials Science and Engineering Program, University of the Philippines Diliman
  • Lorenzo P. Lopez, Jr. Materials Science and Engineering Program, University of the Philippines Diliman
  • Maria Herminia M. Balgos Innovative Photon Manipulation Research Team, RIKEN Wakō
  • Elmer S. Estacio National Institute of Physics, University of the Philippines Diliman
  • Arnel A. Salvador National Institute of Physics, University of the Philippines Diliman
  • Armando S. Somintac National Institute of Physics, University of the Philippines Diliman

Abstract

We investigated how the oxide composition affects the terahertz (THz) emission from n-doped silicon/copper oxide (n-Si/CuxO) heterostructures through THz-time domain spectroscopy (THz-TDS). The n-Si/CuxO heterostructures were grown by thermal evaporation of Cu on a (100) n-Si substrate followed by ex-situ direct thermal oxidation. The Cu-coated n-Si was oxidized in ambient air at different temperatures to control the amount of cuprous oxide (Cu2O) and cupric oxide (CuO) in the CuxO films. Raman spectroscopy showed that at 150°C, an n-Si/Cu/Cu2O stack forms due to the incomplete oxidation of Cu, while an n-Si/Cu2O/CuO stack forms at 250°C. The Cu film was completely oxidized to CuO at 350°C, resulting in an n-Si/CuO stack. Reflectance measurements showed that the CuxO film increases the absorbance of n-Si by more than 8%. THz-TDS measurements showed that the n-Si/Cu2O/CuO heterostructure has the strongest THz emission compared to n-Si/CuO and bare n-Si. The strong THz emission is attributed to (1) the increase in absorption due to Cu2O and CuO, and (2) the built-in electric field at the n-Si/Cu2O interface as explained by band diagram and electric field calculations.

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Published

2023-07-14

Issue

2023: Proceedings of the 41st Samahang Pisika ng Pilipinas Physics Conference

Section

Optics and Photonics

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How to Cite

[1]
“Effects of varying the oxide composition on the terahertz emission of n-Si/CuxO heterostructures”, Proc. SPP, vol. 41, no. 1, pp. SPP–2023, Jul. 2023, Accessed: Mar. 25, 2026. [Online]. Available: https://proceedings.spp-online.org/article/view/SPP-2023-1B-03