Passivation of InSb(100) with 1-Eicosanethiol Self-Assembled Monolayers

Abstract

Due to their higher charge mobility, III-V semiconductors have the potential to replace Si to make faster computer processors that consume less energy. The small bandgap (0.17 eV) of InSb also allows this material to absorb and emit energy in the infrared, making it a key component in infrared detectors for many applications [1]. One disadvantage of III-V semiconductors is their rapid oxidation in air after etching processes and the complex nature of their oxides [2]. Successful chemical passivation and enhancement of electrical properties of various III-V semiconductors with sulfur-containing molecules has been reported in the last years [3]. Zhernokletovet. al.passivated InSb (111)A with a 10 min immersion in a 10% (NH4)2S solution, followed by annealing at 300oC. With this method, low In and Sb oxide levels were obtained after the liquid passivation, and complete oxide removal was achieved after the annealing process. This procedure prevented further oxidation of the InSb substrate, although no mention is made of the passivation time that would be achieved after liquid phase (NH4)2S deposition alone [4]. The goal of this project is to design a liquid-phase process sequence to chemically etch the native oxide and passivate the surface of InSb (100) by depositing an organic layer that prevents oxygen diffusion to the substrate surface and that can be removed when desired. The longest commercially available alkanethiol molecule, 1-eicosanethiol, was chosen to form a self-assembled monolayer (SAM) on the InSb (100) surface.