SOI nanowires as sensors for charge detection

Abstract

The properties of silicon-on-insulator nanowires (SOI NWs) fabricated by means of electron lithography and gas etching of SOI in XeF 2 or SF 6 :CFCl 3 have been investigated. The method used to fabricate the nanowires was found to require no additional anneal to be given to the final structure for defect removal after nanostructuring. The sensitivity of SOI NWs to negative protein BSA molecules in the pH 7.4 buffer solution was shown to be as high as 1 femtomoles. The gate characteristics of SOI NWs were used to determine the charge density of particles adsorbed on the NW surface. A charge density of 4.6 × 10 11 cm −2 was estimated for a 1 femtomole protein concentration. The combined use of open-channel structures with top gates was employed for determining the charge state of structure surfaces after different chemical treatments. Chemical treatments giving rise to a density of the negative charges on the surface of NWs ranging in the interval (7-23) × 10 11 cm −2 were examined. Treatments in methanol (after removal of the native oxide) were found to provide stabilization of the SOI surface over a 3-h interval after the treatments.

SOI-Nanowire Biosensors for High-Sensitivity Protein and Gene Detection

“…In our study, an array of monocrystalline Si nanowires was fabricated using the ''top-down'' approach, through nanostructuring of silicon-on-insulator (SOI) layers achieved using electron-beam lithography and gas or plasma chemical etching [19]. Figure 1a shows an optical and TEM images of SOI NW sensor element of 10-lm length and 90-nm width fabricated in this way.…”

“…It was shown that a NW detector chip prepared in such a way features high sensitivity in registration of protein molecules. Interaction of bovine serum albumin (BSA) with NW surface was observed in solutions with BSA concentrations as low as 10 -14 -10 -15 M [19,20]. In the future, the compatibility of the SOI-NW formation process with the conventional Si CMOS technology, the possibility of scaling down the fabrication of SOI-nano-FETs with arrays of sensor elements will allow production of lowcost NW detectors for high-sensitive clinic medical diagnostics.…”

“…The cost of one measurement cycle, including the cost of the chip and reagents, is within 1,000 dollars [56]. The CMOS-based platform that was developed for registration of pH signals with ion-sensitive transistors can easily be modified to allow operation with SOI NW transistors of ISP SB RAS [19,20,24,36,37] since nanostructuring and NW-FET sensibilization processes are only used at the last, low-temperature stages of the chip fabrication process while the sizes of SOI NW FET detectors, much smaller than the sizes of ion-sensitive transistors, make it possible to raise the total number of sensor cells by a factor of 10-1,000.…”

Existing Biosensing Platforms for the Nucleotide Markers Detection

“…The principle of action for a biosensor based on one-dimensional nanowire as the gate field effect transistor is set up on the effect depending on the flowing through the current transistor from the field on the gate nanowire. The binding of biomolecular marker in the sample with the surface of the sensor element results in a change in its surface potential and, consequently, in an increase in the strength of the current passing through the sensor element, which is fixed by an analog-digital converter [55,56]. This approach allows one to get the exponential dependence of the conductivity of the silicon nanowires on a charge on its surface, thus, to increase the signal/noise ratio and obtain sensitive detection marker molecules to 10 -14 -10 -15 M, which corresponds to the best modern analogues.…”

SOI-nanowire biosensor for the detection of D-NFAT 1 protein

“…Изготовление транзисторов описано в [25,26]. Структуры КНИ имели n-тип проводимости с концентрацией носителей заряда ~6´10 16 cм -3 .…”