Detection of Molecular Charge Dynamics through Current Noise in A GaAs-based Nanowire FET

Abstract

Detection of static and dynamic molecular charge state using a GaAs-based nanowire field-effect transistor (FET) was investigated. Tetraphenylporphyrin (TPP) was put on the device as target molecules. After coating TPP on the FET, the drain current obviously decreased. On the other hand, the current largely increased by 405-nm light irradiation, indicating that TPP worked as photo-excited donor. The light irradiation on the FET also induced Lorentzian noise component, which was superimposed onto conventional 1/f noise.These behaviors were not seen in the gateless nanowire even with TPP. Obtained results indicated that electrical interaction between TPP and the nanowire was enhanced when a metal gate existed, although the channel was protected from TPP by the gate metal. We discuss the observed behaviors on the basis of a model where only TPP in the gate periphery modulated the channel potential and the drain current.2

Detection of some amino acids with modulation-doped and surface-nanoengineered GaAs Schottky P-I-N diodes

“…PLEASE CITE THIS ARTICLE AS DOI: 10.1116/6.0000186 which are attributed to noise originating in: (a) electron trapping and detrapping at the surface of GaAs, (b) tunneling, and (c) thermal activation and random walks of electrons. Some of these peaks need to be understood in the context that, in the first approximation, electronic noise is inversely proportional to energy barrier height, which is affected by the different discrete energy levels associated (φ B ) with the vibrational modes for the tested molecules S n ∝ ∑ 1 35 . So, while "ease of testing" motivates the approach we took here, such approach is not without weaknesses, in part because the peaks in the differential conductance are a combination of quantum transport behavior and noise related to electron transport 35 .…”