Langmuir–Blodgett film passivation of unpinned <i>n</i>-type gallium arsenide surfaces

Abstract

This letter reports the results of the passivation of photochemically unpinned GaAs surfaces using Langmuir–Blodgett (LB) films. Metal-insulator-semiconductor structures are fabricated with LB films as the insulator. The high-frequency capacitance versus voltage measurements show an order of magnitude decrease in the interface trap density (1011 cm−2 eV−1) as compared to the GaAs/anodic oxide interface. The hysteresis in the capacitance versus voltage curves was reduced from a 3-V shift in the flatband voltage, to about a 1-V shift, a level which has been seen in Si/LB film metal-insulator-semiconductor structures. Passivation with LB films is of interest because of their interesting electrical, chemical, and optical properties that can be used in GaAs-based devices.