Electrical characteristics of Si sub 3 N sub 4 /Si/GaAs metal-insulator-semiconductor capacitor

We report on the electrical characteristics of an as-grown Si{sub 3}N{sub 4}/Si/{ital n}-GaAs metal-insulator-semiconductor capacitors. The GaAs layer is grown by molecular beam epitaxy and both the Si{sub 3}N{sub 4} and the 10 A 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 Si{sub 3}N{sub 4} films at high fields can be best represented by Fowler--Nordheim tunneling indicative of the high quality of the films. Hole inversion of the {ital 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 Si{sub 3}N{sub 4}, a hysteresis of less than 100 meV is observed in the high-frequency capacitance-voltage curves with a bias voltage swing of {plus minus}4 V. From the high-low capacitance method we estimated the interface trap density to be of the order of 4{times}10{sup 11} eV{sup {minus}1} cm{sup {minus}2} and from the conductance measurements we found a value of 10{sup 12} eV{sup {minus}1} cm{sup {minus}2}.