Temperature dependence of ultrafast carrier dynamics in intrinsic and nitrogen-doped 6H-SiC crystals

Ultrafast carrier dynamics in intrinsic and nitrogen-doped (N-doped) 6H-SiC crystals is studied by timeresolved two-color pump-probe transmission spectroscopy with temperature ranging from 295 to 12 K. With photoexcitation at 400 nm, and a pump fluence of 5.3 μJ/cm², both samples show ultrafast photoinduced absorption at 800 nm, and the magnitudes of the photoinduced absorption and recovery process have different temperature dependences for both samples, in which the intrinsic 6H-SiC shows almost no temperature dependence, while the magnitudes of the photoinduced absorption and recovery process in N-doped 6H-SiC are temperature dependent. The different temperature dependences of photoinduced absorption and recovery process are due to the different band-gap changes for intrinsic and N-doped 6H-SiC.