Advances in AFM for the electrical characterization of semiconductors

Abstract

Atomic force microscopy (AFM) is a key tool for nanotechnology research and finds its principal application in the determination of surface topography. However, the use of the AFM tip as a probe of electrical properties allows enormous insights into material functionality at the nanoscale. Hence, a burgeoning suite of techniques has been developed to allow the determination of properties such as resistivity, surface potential and capacitance simultaneously with topographic information. This has required the development of new instrumentation, of novel probes and of advanced sample preparation techniques. In order to understand and quantify the results of AFM-based electrical measurements, it has proved important to consider the interplay of topographic and electrical information, and the role of surface states in determining a material's electrical response at the nanoscale. Despite these challenges, AFM-based techniques provide unique insights into the electrical characteristics of ever-shrinking semiconductor devices and also allow us to probe the electrical properties of defects and self-assembled nanostructures.

Nanoscale dielectric microscopy of non-planar samples by lift-mode electrostatic force microscopy

“…nonlocal cantilever contributions), since these contributions are subtracted. It should be noted, that the intrinsic capacitance gradient is still dependent on the sample geometry and dimensions since they determine the overall electric polarization of the sample, and hence, the force acting on the tip [31][32][33][34]. Experimentally the topographic crosstalk capacitance gradient image can be constructed following the procedure that we applied for the case of capacitance measurements in Ref.…”

“…As a consequence, the tip-substrate distance varies during the image acquisition, thus inducing spurious capacitance variations that are not related to the dielectric properties of the sample. That is, dielectric images of non-planar samples can be severely affected by topographic crosstalks [31][32][33][34].…”

Single cycle and transient force measurements in dynamic atomic force microscopy

“…The instrument is currently employed by researchers in elds ranging from biology 8,9 to semiconductor theory and devices 10 and in hybrid systems. 11 With the AFM one can routinely image single nanostructures, 12,13 map heterogeneous compositional [14][15][16][17][18] and/or nanomechanical [19][20][21] properties and/ or processes, 22,23 study molecular interactions 24,25 and larger biological systems, 26,27 identify single atoms, 28 molecules 29,30 and/or chemical composition 31 and structures, 32 study the friction induced by single atomic motion 33 and, more recently, even discriminate bond order and symmetry.…”

The importance of cantilever dynamics in the interpretation of Kelvin probe force microscopy

“…[1][2][3] Among the many EFM techniques, Kelvin probe force microscopy (KPFM) has proven to be a powerful technique to measure the local work function. [4][5][6][7] A central challenge in KPFM is to achieve nanoscale spatial resolution, despite the large size of the probe and the long range of the electrostatic interaction.…”