Anodic Al2O3/InP MIS interface and its application to enhancement-MISFET's on semi-insulating substrates

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Abstract
A simple process to grow anodically high-quality Al2O3, films on InP substrates with good adhesion, is described. The AGW electrolyte is employed. The resultant oxide is uniform and possesses resistivity values in excess of 1015 Ωcm with a breakdown field strength of about 2–3 × 106 V/cm. Properties of anodic Al2O3/InP interfaces arc clarified by quasi-static capacitance-voltage and dynamic DLTS and photo-ionization techniques. The results are. consistent, and indicate that the distribution of interface states in U-shaped in the upper half of the bandgap, making a sharp contrast to the case of GaAs MIS systems. The anodic Al2O3n-InP MIS interface exhibits extremely small frequency dispersion on the accumulation side, and the surface Fermi level can be brought up as close as 0[sdot]05 eV to the conduction band edge. Using the present Al2O3, films, n-channel enhancement MISFET's were successfully constructed directly on Fe-doped semi-insulating substrates with the channel mobility of 300 cm2/Vs.