Electrical characteristics of Si3N4/Si/GaAs metal-insulator-semiconductor capacitor

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Abstract
We report on the electrical characteristics of an as-grown Si3N4/Si/n-GaAs metal-insulator-semiconductor capacitors. The GaAs layer is grown by molecular beam epitaxy and both the Si3N4 and the 10 Å Si layers are deposited using silane in a vacuum connected ultrahigh vacuum chemical vapor deposition chamber driven by an electron cyclotron resonance plasma source. The current-voltage characteristics of the Si3N4 films at high fields can be best represented by Fowler–Nordheim tunneling indicative of the high quality of the films. Hole inversion of the n-GaAs layer is clearly seen in the quasi-static capacitance-voltage curve. Despite past reports on the presence of a large amount of bulk traps in Si3N4, a hysteresis of less than 100 meV is observed in the high-frequency capacitance-voltage curves with a bias voltage swing of ±4 V. From the high-low capacitance method we estimated the interface trap density to be of the order of 4×1011 eV−1 cm−2 and from the conductance measurements we found a value of 1012 eV−1 cm−2.