Papers by Author: A.V. Bolotnikov

Abstract: Doubly-implanted SiC vertical MOSFETs were fabricated displaying a blocking voltage of 4.2kV and a specific on-resistance of 23 mΩ-cm2, on a 4.5mm x 2.25mm device. Design variations on smaller (1.1mm x 1.1mm) devices showed on-resistance as low as 17 mΩ-cm2 with a blocking voltage of 3.3kV. Analysis is presented of the on-resistance and temperature dependence (up to 175°C), as well as switching performance. Switching tests taken at 1000V and 6A showed turn-on and turn-off transients of approximately 20-40ns.

Abstract: In this work the analysis of thermal diffusion of boron carried out from vapor phase was performed. Two-branch diffusion associated with kick-out and substitution mechanisms was observed. The activation energy and prefactor were calculated from Arrhenius plot for each diffusion branch. It has been established that the surface layer of diffused boron mostly consists of shallow boron acceptors, while the tail of the diffusion profile has mostly deep level D centers.

Abstract: In this work we report the measurement of minority carrier lifetimes using the time resolved photoluminescence technique. It was found that 4H-SiC homo-epilayers grown using chlorine-based precursors have longer carrier lifetimes if used in conjunction with a tantalum carbide coated (TaC-coated) graphite susceptor rather than a SiC-coated graphite susceptor. Longer carrier lifetimes were obtained by optimal combinations of precursor gases and susceptor type. The controllable variation in lifetime from 250 ns to 9.9 s was demonstrated.

Abstract: The degradation of diffused SiC PIN diodes during forward-biased operation was studied by first fabricating PIN diodes by diffusion of aluminum or boron into 4H-SiC substrates with n-type 10-15 µm thick epilayers doped by nitrogen up to 5x1015cm-3. The formed diodes were subjected to degradation testing under an applied current density of 200A/cm2 at room temperature. The majority of the Al diffused diodes demonstrated a voltage drift, ΔVf, of more than 2 V, while B-doped diodes showed no significant change in forward voltage. The EBIC mode of SEM was employed to monitor nucleation and expansion of stacking faults.