Abstract
Surface-exposed uniformly doped silicon-on-insulator channels are fabricated to evaluate the accuracy of Kelvin Probe Force Microscopy (KPFM) measured surface potential and reveals the role of surface charge on the exposed channel operated in the ambient environment. First, the quality of the potential profile probed in the vacuum environment is assessed by the consistency of converted resistivity from KPFM result to the resistivity extracted by the other three methods. Second, in contrast to the simulated and vacuum surface potential profile and image, the ambient surface potential is bent excessively at the terminals of the channel. The excessive bending can be explained by the movement of surface charge under the drive of geometry induced strong local electric field from the channel and results in non-uniform distribution. The dynamic movement of surface charges is proved by the observation of time-dependent potential drift in the ambient measurement. The result suggests the surface charge effect should be taken into account of the measurement of the surface potential in the ambient environment and the design of charge sensitive devices whose surfaces are exposed to air or in ambient conditions in their operation.
Highlights
The result suggests the surface charge effect should be taken into account of the measurement of the surface ce potential in the ambient environment and the design of charge sensitive devices whose surfaces are exposed to air or in ambient conditions in their operation
We present accurate extraction of the actual local potential drop in the channel linking with the local resistivity evaluation of the devices, and the observation of novel dynamic surface dM
Taken in ambient condition from those taken in vacuum indicates how the surface charges respond to the internal biasing applied to the conducting channels
Summary
High-resolution topography and local potential image together are a very powerful tool to understand us cri the local environment of nanoelectronic devices, for example, the dopants fluctuation in nanowires [1,2,3], defects in nanowires [4] and 2D materials [5], junction formation in various nanostructures [6,7,8,9,10,11], band bending in crystal grains boundaries [12,13], the surface potential change on sensors [14,15,16,17,18,19,20]. The local electrical potential is associated with the properties of materials or device themselves and with the measurement environment [29,30,31], applied bias induced local charge trapping or injection [30,32,33,34], and ion transportation [35] This dynamic surface potential change is not well studied but important, associated with various kinds of nanoscale charge sensitive devices, pte especially for sensing applications. KPFM [36] has been developed to extract the high-resolution potential image from micro- and nanostructures It is based on the technique of Atomic Force Microscope (AFM) that can detect nanonewton-level force change between the cantilever and sample with the distance of less than 5 nm. We present accurate extraction of the actual local potential drop in the channel linking with the local resistivity evaluation of the devices, and the observation of novel dynamic surface charge redistribution under the ambient condition that has been identified after the intensive analysis of the surface potential data taken under various conditions
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