Depth-Resolved Carrier Lifetime Measurements in 4H-SiC Epilayers Monitoring Carbon Vacancy Elimination

Augustinas Galeckas; Hussein M. Ayedh; J. Peder Bergman; Bengt Gunnar Svensson

doi:10.4028/www.scientific.net/MSF.897.258

Paper Titles

New Efficient Canal of THz Emission from SiC Natural Superlattices in Conditions of Wannier-Stark Localization
p.242

Point Defects Investigation of High Energy Proton Irradiated SiC p⁺-i-n Diodes
p.246

New Evidence for the Second Conduction Band in 4H SiC
p.250

On Electrons Mobility in Heavily Nitrogen Doped 4H-SiC
p.254

Depth-Resolved Carrier Lifetime Measurements in 4H-SiC Epilayers Monitoring Carbon Vacancy Elimination
p.258

Formation of D-Center in p-Type 4H-SiC Epi-Layers during High Temperature Treatments
p.262

Density Functional Theory on NV Center in 4H SiC
p.269

Comparative Study of p-Type 4H-SiC Grown on n-Type and Semi Insulating 4H-SiC Substrates
p.275

DLTS Study on Al⁺ Ion Implanted and 1950°C Annealed p-i-n 4H-SiC Vertical Diodes
p.279

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Depth-Resolved Carrier Lifetime Measurements in 4H-SiC Epilayers Monitoring Carbon Vacancy Elimination

Abstract:

We address the key factors limiting charge carrier lifetime in 4H-SiC epilayers by demonstrating a viable method for eliminating carbon vacancy (V_C) related Z_1/2 lifetime killer sites and by introducing a novel approach in depth-resolved characterization of the carrier lifetimes across the epitaxial layer, which allows monitoring the efficacy of the proposed defect reduction scheme also exposing surface and interface recombination effects. We show that a moderate-temperature annealing conducted at 1500 °C for 6 hours under C-rich thermodynamic equilibrium conditions in effect eliminates carbon vacancies in epilayers to the levels below the detection limit (10¹¹ cm^-3) of DLTS measurements. The efficient reduction of V_C-related Z_1/2 sites upon thermal treatment is further proven by a significant increase of the minority carrier lifetime from 0.3µs to 1 µs, the upper limit apparently set by epilayer thickness dependent lifetime. Equally important is the extensive range of defect elimination as evidenced by consistently enhanced lifetime throughout entire 40 μm-thick epilayer, thus suggesting immediate practical implication as a lifetime control method suitable for variable thickness 4H-SiC epilayers.