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Cross-sectional carrier lifetime profiling and deep level monitoring in silicon carbide films exhibiting variable carbon vacancy concentrations

Abstract

We report on the carrier lifetime control over 150 μmthick 4H-SiC epitaxial layers via thermal generation and annihilation of carbon vacancy (VC) related Z1/2lifetime killer sites. The defect developments upon typical SiC processing steps, such as high- and moderate-temperature anneals in the presence of a carbon cap,are monitored by combining electrical characterization techniques capable of VC depth-profiling, capacitance-voltage (CV) and deep-level transient spectroscopy (DLTS), with a novel all-optical approach of cross-sectional carrier lifetime profiling across 4H-SiC epilayer/substrate based on imaging time-resolved photoluminescence (TRPL) spectroscopy in orthogonal pump-probe geometry,which readily exposes in-depth efficacy ofdefect reduction and surface recombination effects.The lifetime control is realized byinitialhigh-temperature treatment (1800ºC) to increase VC concentration to ~1013 cm-3 level followed by a moderate-temperature (1500ºC) post-annealing of variable duration under C-rich thermodynamic equilibrium conditions. The post-annealing carried out for 5 hours in effect eliminates VCthroughout the entire ultra-thick epilayer. The reduction of VC-related Z1/2 sites is proven by a significant lifetime increase from 0.8 μs to 2.5 μs. We discuss the upper limit of lifetimes in terms of carrier surface leakage and presence of other non-radiative recombination centers besides Z1/2, possibly related to residual impurities such as boron.

Category

Conference lecture

Language

English

Author(s)

  • Augustinas Galeckas
  • Robert Michael Karsthof
  • Kingsly Gana
  • Angela Kok
  • Marianne Etzelmüller Bathen
  • Lasse Vines
  • Andrej Kuznetsov

Affiliation

  • SINTEF Digital / Smart Sensors and Microsystems
  • University of Oslo

Presented at

The 4th International Conference on Radiation and Emission in Materials

Place

Pattaya

Date

06.04.2022 - 08.04.2022

Year

2022

View this publication at Norwegian Research Information Repository