GaAs Interfaces with Octadecyl Thiol Self-Assembled Monolayer: Structural and Electrical Properties

A passivation layer on chemically etched (100) GaAs surface was synthesized with octadecyl thiol, CH 3 (CH 2 ) 17 SH, and its structural and electrical properties were investigated. The layer is a self-assembled monolayer (SAM) in all-trans-planar-zig-zag conformation and is the first conformationally ordered SAM on any semiconductor surface. The barrier height of GaAs Schottky diodes can be modified by the octadecyl thiol SAM passivation without sacrificing good diode characteristics. Octadecyl and other alkane thiol SAM's enable introduction of a nano-scale, controlled structure on a GaAs surface and prove useful in an assessing the GaAs surface electrical properties.