Observation of a two dimensional electron gas formed in a polarization doped C-face 3C/4H SiC heteropolytype junction

A two dimensional electron gas (2DEG) was observed in a C-face 3C/4H SiC heteropolytype junction. Sheet carrier concentrations of similar to 3x10(13) cm(-2) and Hall mobility of similar to 314 cm(2)/V s were measured at 77 K. The temperature dependences of mobility and carrier concentration clearly demonstrate the presence of the 2DEG. Comparison with theory indicates that the carriers originate from both spontaneous polarization and unintentional degenerate nitrogen doping of 3C-SiC, suggesting a 77 K 2DEG mobility similar to 700 cm(2)/V s in parallel with bulk hopping conduction. Mobility at high temperatures was phonon limited, indicating a Debye temperature of 1600 K. Transmission line measurements yielded similar mobilities, with saturation currents of similar to 3 A/mm, suggesting the utility of SiC heteropolytypes in microwave devices. (C) 2007 American Institute of Physics.