Title :
Steady-state and transient forward current-voltage characteristics of 4H-silicon carbide 5.5 kV diodes at high and superhigh current densities
Author :
Dyakonova, Nina V. ; Ivanov, Pavel A. ; Kozlov, Vladimir A. ; Levinshtein, M.E. ; Palmour, John W. ; Rumyantsev, S.L. ; Singh, Ranbir
Author_Institution :
A.F. Ioffe Physicotech. Inst., Acad. of Sci., St. Petersburg, Russia
fDate :
11/1/1999 12:00:00 AM
Abstract :
Steady-state and transient forward current-voltage I-V characteristics have been measured in 5.5 kV p+-n-n+ 4H-SiC rectifier diodes up to a current density j≈5.5×10 4 A/cm2. The steady-state data are compared with calculations in the framework of a model, in which the emitter injection coefficient decreases with increasing current density. To compare correctly the experimental and theoretical results, the lifetime of minority carriers for high injection level, τph, has been estimated from transient characteristics. At low injection level, the hole diffusion length Lpl has been measured by photoresponse technique. For a low-doped n-base, the hole diffusion lengths are Lpl≈2 μm and Lph≈6-10 μm at low and high injection levels respectively. Hole lifetimes for low and high injection levels are τpl≈15 ns and τph≈140-400 ns. The calculated and experimental results agree well within the wide range of current densities 10 A/cm 2<j< 4×103 A/cm2. At j>5 kA/cm2, the experimental values of residual voltage drop V is lower than the calculated ones. In the range of current densities 5×103 A/cm2<j<2×104 A/cm2, the minimal value of differential resistance Rd =dV/dj is 1.5×10-4 Ω cm2. At j>25 kA/cm2, Rd increases with increasing current density manifesting the contribution of other nonlinear mechanisms to the formation steady-state current-voltage characteristic. The possible role of Auger recombination is also discussed
Keywords :
carrier lifetime; minority carriers; power semiconductor diodes; silicon compounds; solid-state rectifiers; wide band gap semiconductors; 4H-silicon carbide p+-n-n+ rectifier diode; 5.5 kV; Auger recombination; SiC; current density; current-voltage characteristics; differential resistance; emitter injection coefficient; hole diffusion length; minority carrier lifetime; photoresponse; residual voltage drop; steady-state characteristics; transient characteristics; Current density; Current measurement; Current-voltage characteristics; Density measurement; Diodes; Length measurement; Life estimation; Lifetime estimation; Rectifiers; Steady-state;
Journal_Title :
Electron Devices, IEEE Transactions on