Si3N4/Si/Ge/GaAs metal-insulator-semiconductor structures grown by in situ chemical vapor deposition

The in situ, heteroepitaxial growth of Ge films grown on (100) n-GaAs, followed by in situ deposition of a Si3N4/Si insulator to form a Ge metal-insulator-semiconductor structure, is reported. The growth of the Ge, Si, and Si3N4 is carried out in an ultrahigh vacuum, chemical vapor deposition system which is vacuum connected to an adjacent III-V molecular beam epitaxy machine in which the GaAs is grown. The Ge is grown at low temperature (250 °C) using GeH4 and excited He from a remote plasma. After a rapid thermal annealing step, a marked reduction in hysteresis is observed in the capacitance-voltage characteristics and the density of interface trap states at the Si3N4/Si/Ge interface, as determined from the magnitude of the conductance peak, is found to decrease by a factor of 5, to 1×1011 eV−1 cm−2.