OCVD Lifetime Measurements on 4H-SiC Bipolar Planar Diodes: Dependences on Carrier Injection and Diode Area

In this paper, open-circuit voltage decay measurements of carrier lifetimes on 4H silicon carbide ion implanted planar p-i-n diodes of circular shape and different diameters are performed at increasing bias currents. The measured ambipolar carrier lifetimes have shown to be dependent on the carrier injection levels, quickly increasing at low-bias current up to reaching a saturation value, τ
_HL
, when the value of the average carrier density within the base exceeds the intrinsic-region doping. The τ
_HL
measured in diodes of different area also demonstrate a marked dependence on the diode dimension, with longer lifetimes being typical of larger-diameter diodes, suggesting that a great contribution of recombination comes from the diode periphery. A bulk ambipolar lifetime τ
_{HL_Vol}
= 320 ns has been extracted from the area-dependent measured lifetimes.