Room Temperature Single-Electron Narrow-Channel Memory with Silicon Nanodots Embedded in SiO₂ Matrix

Abstract

The room-temperature operation of a single-electron narrow-channel memory device has been demonstrated by the combined fabrication of a narrow-channel (20 nm wide by 80 nm long) field-effect transistor (FET) defined by electron-beam lithography and nanocrystalline Si (nc-Si) dots formed by annealing a thin film of SiO x (x<2). Electrons are injected into nc-Si floating gate dots in discrete units, as observed by the stepwise increase in the threshold shift with writing bias, which is expected for Coulomb repulsion within the nc-Si dot. Time-dependent measurement of the channel current under the floating gate shows stepwise loss of charge, with a lifetime of each stored electron of about 500 s at room temperature. Measurements at low temperature (20 K) show similar discrete steps in memory writing.

Evidence of storing and erasing of electrons in a nanocrystalline-Si based memory device at 77 K

“…Considering the fact that each step in the conduction corresponds to the emission of each electron, one can conclude one of the two electrons from the nc-Si dot having a retention time of about 30 s, was erased. The fact that there is an abrupt and steplike increase in channel current instead of a continuous increase in between the steps as observed by Yun et al 13 due to participation of several dots in screening the channel, confirms a memory operation determined by a single dot. Moreover, Fig.…”

Operation of nanocrystalline-silicon-based few-electron memory devices in the light of electron storage, ejection, and lifetime characteristics

“…4(a) that the electron, which is trapped during scan-I, is not emitted from the dotasnostep-likeincreaseinconductionisexhibited,whereasjust one discrete step with a time period of approximately 30 s is ob- served in Fig. 4(b), which can be associated with emission of one ofthestoredelectrons,asevidencedinFig.2(a).Itisworthwhileto mentionthattheabruptchangeinthechannelcurrentisalsoconsistent with the hypothesisthat only one nc-Si dot in the activeregion of the device contributes in the memory operation [11]. We argue that the trapped electrons would reside in the conduction band the nc-Si dot.…”

Electrical characterisation of Si‐SiO2 structures

“…The reason is their promising application in nonvolatile memories [1], third generation solar cells [2] and single-electron devices [3]. These structures have predominantly been studied by structural and optical characterization techniques, such as transmission electron microscopy (TEM), infrared absorption spectroscopy (IR) and photoluminescence (PL).…”