Semiconductor Surface Chemical Modification Method And Their Optical And Electrical Properties

With the development of nanoelectronics and molectronics, great attention has been paid to the covalently bonded hybrid of organic monolayer and semiconductor in recent years. Semiconductor plays an important role as the platform for the study of nanoscope and even single molecule in photonics and electronics. The hybrids have extensive applications in switch, information storage, transistor, sensor and etc. Stimulus-responsive molecules modified semiconductor is of great importance in the development of intelligent electronic devices. We have studied silicon and diamond surface which were modified with functional molecules on photonic and electronic behaviors. The main contents are as follows:1,Photoresponsive azobenzene molecule 4-N,N-dimethylamino-4'-ethynyl-azobenzene (DMAEAB) was synthesized. DMAEAB molecules were covalently grafted onto hydrogen-terminated Si(111) surface through photochemical reaction with Si-C as linkages. The modified surfaces were characterized by wettability, X-ray photoelectron spectroscopy (XPS) and attenuated total re?ectance Fourier transform infrared (ATR-FTIR) spectroscopy. The reversible photoisomerization effects of the DMAEAB monolayer were studied with contact angle measurements, atomic force microscopy (AFM), and conductive-probe atomic force microscopy (CP-AFM). The two isomers of DMAEAB on Si(111) showed clearly difference in wettability, topography, and conductance. Molecularly controlled modulation of conductance of the DMAEAB modified Si surface was realized by applying special light. The hybrid of DMAEAB monolayer and silicon has potential applications in optical switch, information storage and etc.2,Boron-doped diamond (BDD) films have been fabricated through chemical vapor deposition (CVD). The diamond films were characterized by Raman spectroscopy. The morphology was observed with SEM, and topography was monitored with AFM. The conductive performance was analysed with CP-AFM and four-probe digital multimeter. Monolayer of the viny-ended azobenzene DOAA was prepared on BDD film through photochemical reaction between the vinyl and the C-H bond of the plasma-processed BDD surface. The monolayer was characterized by XPS and ATR-IR spectroscopy. DOAA monolayer showed high stability when it was suffered to corrosive solvents. The photoelectrochemical behaviors of DOAA monolayer was analyzed by cyclic voltammetry with BDD film as the working electrode, and the two isomers of DOAA exhibited clearly diffenent electrochemical behavior. In addition, the results also demonstrate that BDD films are excellent platform for study of redoxactive molecular monolayer's electrochemical behaviors.3,Vinyl-terminated diacetylene derivative DA-4AS was synthesized. DA-4AS monolayer was prepared on silicon wafer via photochemical reaction between DA-4AS and hydrogen-terminated Silicon. The monolayer was characterized with XPS, spectroscopic ellipsometry, ATR-IR and contact angle measurement. Most importantly, we developed a method which can be used to fabricate PID( polydiacetylene and its derivative) matrix with the diameter as 5μm and the center-to-ceneter distance 20μm based on the unique photochemical reaction of diacetylene. The matrix was monitored with AFM, and the fluorescence patterning was observed under confocal fluorescence spectroscopy after further heat of the matrix. In short, a new approach was developed for fabrication of PID matrix which laid groundworks for fabrication of PID based chemo/biochips.