Advanced characterization of density-of-states over wide bandgap-energy in p-type Cu2O TFTs by multiple-wavelength light source

Abstract

In this study, we fabricated thin-film transistors by depositing Cu2O through plasma-enhanced atomic layer deposition (3.6 k cycles), which has the advantages of enhanced chemical reactivity and improved crystal structure of thin films compared to conventional atomic layer deposition. We analyzed traps near the valence band using multi-wavelength light that extended up to the above bandgap, in conjunction with dark-state measured data. Using multi-wavelength light, we extracted traps dependent on the gate voltage. Traps with underestimated density due to limited detectability within the bandgap, dependent on the energy levels of the wavelengths, are filled with photons to extract the captured traps (holes). Our results reveal that the energy-dependent density peaks of VCu and VO, which strongly influence the p-type conduction mechanism, were observed in the trap density near the Fermi level using multiwavelength I–V photo-response. This study reports photo-responsive I–V measurements in aggressively scaled devices, crucial for instability and reliability assessments. Furthermore, trap extraction plays a critical role in the effective integration of n-type oxide semiconductors into CMOS technology, providing valuable insights into the performance analysis of applications.