Surface charging of silicondioxide/silicon structures

Abstract

The surface of silicondioxide/silicon structures is charged with the tip of a cantilever in contact mode by application of a voltage. Then, the surface potential is measured contactless using the Kelvin option of an atomic force microscope. On the position of the charged domain a potential difference in relation to the uncharged region is found. It turns out that the height and the width of this potential difference depend on the charging time, on the height of the charging voltage, on the sample thickness, and on the doping of the siliconsubstrate. Furthermore, a time dependent spread and a decay of the surface potential are observed. For dry samples the decay is slower than for wetted samples. Due to this long-term stability at dry samples and the possibility to reverse the sign of the deposited charge by recharging in opposite direction it is thinkable to use the system as a surface charge memory device.

Direct probing of electron and hole trapping into nano-floating-gate in organic field-effect transistor nonvolatile memories

“…In particular, KPFM is powerful to study surface work function, [18][19][20] band bending and interfacial dipole, [21][22][23][24][25] and also employed to quantitatively evaluate charge quantity trapped in insulators. [26][27][28][29][30] In this report, KPFM is used to simulate programming/ erasing process and directly profile charge trapping into the nano-floating-gate in a pentacene-based OFET nonvolatile memory. It is demonstrated that the integration of surface potential change (DW) after programming/erasing reflects the quantity of electron/hole trapping.…”

“…N 2 gas was flowed in the measuring chamber to maintain a low humidity ($20%), as humidity may influence surface charge diffusion. 26,28 The KPFM instrument was operated in the Peak Force tapping mode, 33 with scanner oscillation frequency f 0 of 2 kHz and amplitude of 150 nm. This offers a precise force control between the probe and sample surface and allows non-destructive potential probing on soft materials such as organic thin films, preserving their surface morphology during scanning.…”

Research of MEMS pressure sensor stability with PDA-NFL circuit

“…There are two main factors for piezoresistive pressure sensor chips that affect the useful signal and errors. The first factor is related to leakage currents of pressure sensor chip due to the limiting ability of closing the p-n junction for high and low-alloyed regions of piezoresistors (PRs) on wafers with single-crystal structure [24][25][26][27], defectivity [28] and embedded charge in the surface silicon oxide [29], and due to the effect of the difference in the temperature coefficient of expansion (TCE) between aluminum (or other metal) and silicon on the thin membrane structure [30][31][32]. The second factor is the relaxation of residual mechanical stresses (RMS) in the micro-assembly structure of pressure sensor chip [33][34][35][36][37].…”