THERMAL-STABILITY OF SI3N4 SI GAAS INTERFACES

An investigation on the thermally induced interface degradation of Si3 N4/Si/p-GaAs metal-insulator-semiconductor (MIS) structures is present ed. We characterize the mutation of chemical identities by in situ ang le-resolved x-ray photoelectron spectroscopy and the nature of an insu lator and interface by a variable angle spectroscopic ellipsometry aft er high temperature annealing. The minimum interface state density of the Si3N4/Si/p-GaAs MIS capacitor as determined by capacitance-voltage and conductance loss measurements was about 8x10(10) eV(-1) cm cm(-2) near GaAs midgap after rapid thermal annealing at 550 degrees C in N- 2. However, this density increased to 5x10(11) eV(-1) cm(-2) after ann ealing at 750 degrees C in N-2. The underlying mechanisms responsible for this degradation are described. (C) 1997 American Institute of Phy sics.