Metal/molecule/silicon electronic devices: Realizing hybrid semiconductor/organic functionality.

摘要

Recently there has been significant interest in incorporating molecular elements into electronic devices for electronics, memory, and chemical/biological sensing applications. To date much of the work on this topic has utilized metal electrodes however using silicon (Si) presents physical and technological advantages. Molecules can be covalently bound to Si surfaces. Device properties can be tailored both by changing the surface chemistry and by doping the Si. Moreover, Si is technologically relevant for electronics applications. This study focuses on the development, characterization, and modeling of metal/molecule/Si (MMS) devices. Si surfaces have been functionalized with various organic species and the resulting molecular layers have been characterized using a variety of surface-analysis techniques. The structural and chemical properties of metallized molecular layers have been characterized using in-situ spectroscopic measurements. MMS devices with various molecular layers, Si doping types, and doping densities have been fabricated and electrically characterized using capacitance-voltage and temperature-dependent current-voltage measurements. A model has been developed in which MMS devices are described by a four-layer structure consisting of the metal, the molecular layer, the Si surface, and the Si bulk. Electronic transport is modulated by the molecular layer, which acts as a tunnel barrier with a transmission coefficient that depends on the molecular-electronic structure, and the Si surface, which can be accumulated or depleted depending on the device electrostatics. In the MMS devices developed and analyzed in the study, electronic transport is governed by the interplay between the molecular-electronic properties and Si bandstructure, enabling novel hybrid organic/semiconductor functionality.