A pH sensor with a double-gate silicon nanowire field-effect transistor Appl. Phys. Lett. 102, 083701 (2013) The transport, noise, and photosensitivity properties of an array of silicon nanowire (NW) p þ -p-p þ field-effect transistors (FETs) are investigated. The peculiarities of photosensitivity and detectivity are analyzed over a wide spectrum range. The absorbance of p-Si NW shifts to the short wavelength region compared with bulk Si. The photocurrent and photosensitivity reach increased values in the UV range of the spectrum at 300 K. It is shown that sensitivity values can be tuned by the drain-source voltage and may reach record values of up to 2-4 A/W at a wavelength of 300 nm at room temperature. Low-frequency noise studies allow calculating the photodetectivity values, which increase with decreasing wavelength down to 300 nm. We show that the drain current of Si NW biochemical sensors substantially depends on pH value and the signal-to-noise ratio reaches the high value of 10