Dopant atom clustering and charge screening induced roughness of electronic interfaces in GaAs<i>p-n</i>multilayers

Jäger, N. D.; Urban, K.; Weber, E. R.; Ebert, Ph.

doi:10.1103/physrevb.65.235302

Cited by 10 publications

(3 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In such conditions, statistical fluctuations in the dopant distribution become particularly important. 1,2 Inhomogeneities in the dopant distribution 3 may cause nanoscale and atomic-scale fluctuations in the potential, 4 which in turn would lead to a statistical lowering of the threshold voltages. 1 However, in other cases, no effect of the spatial positions of charged defects on the local potential was found.…”

mentioning

confidence: 99%

Origin of nanoscale potential fluctuations in two-dimensional semiconductors

Landrock

Jiang

et al. 2009

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

We demonstrate a direct atomically resolved visualization and quantification of the impact of inhomogeneities in the dopant distribution on the nanoscale potential fluctuations in a two-dimensional semiconducting ͱ 3 ϫ ͱ 3 Ga overlayer on Si͑111͒ using scanning tunneling microscopy. By a quantitative analysis, two regimes of the potential at nanometer scale are found, which arise from the local distribution of charge carriers in the bands and from electron-electron interactions.With the ongoing push for smaller semiconductor devices, the feature size implemented in current commercial manufacturing processes is reaching dimensions, where ultimately the device operation depends on a single electron and traditional device concepts break down. In such conditions, statistical fluctuations in the dopant distribution become particularly important. 1,2 Inhomogeneities in the dopant distribution 3 may cause nanoscale and atomic-scale fluctuations in the potential, 4 which in turn would lead to a statistical lowering of the threshold voltages. 1 However, in other cases, no effect of the spatial positions of charged defects on the local potential was found. 5 This inconsistency is essentially due to the lack of solid experimentally proven facts about the effect of nanoscale dopant inhomogeneities on the local nanoscale and atomic-scale potential. It is still unclear which physical mechanisms determine the nano-and atomicscale potential and which quantitative models can be used for accurate simulations of the potential in spatially ͑and/or dimensionally͒ reduced semiconductor structures. Therefore, we illustrate here a direct atomically resolved visualization and quantification how dopant atoms and their statistical distribution affect the local nanoscale and atomicscale potential using scanning tunneling microscopy ͑STM͒. We identify two different origins of the nanoscale potential and derive a quantitative physical understanding of dopantinduced potential fluctuations at nanometer and subnanometer scales. As a model system, we utilize a two-dimensional ͑2D͒ ͱ 3 ϫ ͱ 3 Ga on Si͑111͒ structure, where we can tune the dopant concentration over a wide range by suitable adjustment of the deposition parameters. Figure 1͑a͒ shows an atomically resolved constant-current STM image of our model system: each maximum in the empty state STM image corresponds to one empty dangling bond above a Ga adatom. The weaker maxima ͑marked D͒, whose concentration decreases with increasing Ga deposition, arise from Si atoms located on ͱ 3 ϫ ͱ 3 Ga sites. 6 These Si atoms act as donors and provide the free electrons. 7 The resulting positive charges of the Si dopants induce a redistribution of the free charge carriers and thereby a potential change, which gives rise to the surrounding bright contrast on which the atomic corrugation is superimposed. 8 The local potential change also shows up in the tunneling spectra: the valence ͑E V ͒ and conduction band ͑CB͒ edges ͑E C ͒ shift Ϸ0.15 eV to higher energies with increasing spatial separation from the d...

show abstract

mentioning

confidence: 99%

Origin of nanoscale potential fluctuations in two-dimensional semiconductors

Landrock

Jiang

et al. 2009

Applied Physics Letters

Self Cite

View full text Add to dashboard Cite

show abstract

“…Experimental methods beyond PL have also been attempted with such a variety of techniques as scanning tunneling microscopy, microprobe absorption/reflectance spectroscopy, and spectral photoelectric measurements in report. [ 27–35 ] However, most of those techniques need specific equipment setups, which are often complex requiring extra skills. Here, we introduce a relatively simple method to measure the bandgap of multilayer 2D semiconductors; that is utilizing field effect transistor (FET) as a platform, which is but using multilayer graphene (multi‐LG, thin graphite) contact for source and drain (S/D).…”

Section: Introductionmentioning

confidence: 99%

Measuring the Bandgap of Ambipolar 2D Semiconductors using Multilayer Graphene Contact

et al. 2022

View full text Add to dashboard Cite

The bandgaps of monolayers and few layers in 2D semiconductors are usually measured by optical probing such as photoluminescence (PL). However, if their exfoliated thickness is as large as a few nanometers (multilayer over ≈5 L), PL measurements become less effective and inaccurate because the optical transition of a 2D semiconductor often changes from direct to indirect mode. Herein, a simple method to approximately estimate the bandgap of multilayer 2D van der Waals (vdW) semiconductors is introduced; that is utilizing a field‐effect transistor (FET) as a platform. Multilayer graphene (multi‐LG) contact for multilayer van der Waals channels in the FET is used, because multi‐LG contact would secure ambipolar behavior and somewhat enable Schottky barrier modulation in contact with vdW channels. As a result, the bandgaps of multilayer transition‐metal dichalcogenides (TMDs) and black phosphorus in unknown thicknesses are approximated through measuring the temperature‐dependent transfer curve characteristics. The bandgaps are confirmed with photoelectric responsivity measurements, which evidences the validity of the multi‐LG‐induced approximation.

show abstract

“…7 This technique allowed to investigate with atomic resolution the compositional distributions as well as roughness of semiconductor interfaces 8 and related nanostructures, such as quantum dots 9 and provides a distinction between atomic ͑chemical͒ and electronic interfaces. 10 The STM is in addition sensitive to potential fluctuations and thereby allows to probe the local potential, e.g., around charged defects 11 or induced by fluctuations in the dopant distribution. 12 Beyond electronic sensitivity, the spinpolarized STM, based on specially prepared magnetic tips, 13 provides even an atomically resolved view of the spin structure of surfaces.…”

Section: Introductionmentioning

confidence: 99%

In situ manipulation of scanning tunneling microscope tips without tip holder

Raad

Graf

Ebert

2010

Review of Scientific Instruments

Self Cite

View full text Add to dashboard Cite

A design for a manipulator system for manipulating bare scanning tunneling microscopy (STM) tips without any tip holder is presented. The extremely stiff and rigid system consists of an ultrahigh vacuum compatible fully three-dimensionally movable gripper module driven by stepping motors and piezomotors. The tips are clamped by hardened tool steel gripper jaws, which are controlled by a stepping motor through levers. The system allows the reproducible manipulation of bare tungsten tips made of wires with diameters of 0.25 nm and having length of only up to 3 mm without damaging the tip or the STM. The tip manipulators’ advantage is that the total mass of the scanning piezotube is reduced by removing the mass of a separate tip holder. Thereby, it becomes possible to further increase the resonance frequencies of the STM.

show abstract

Dopant atom clustering and charge screening induced roughness of electronic interfaces in GaAsp-nmultilayers

Cited by 10 publications

References 17 publications

Origin of nanoscale potential fluctuations in two-dimensional semiconductors

Origin of nanoscale potential fluctuations in two-dimensional semiconductors

Measuring the Bandgap of Ambipolar 2D Semiconductors using Multilayer Graphene Contact

In situ manipulation of scanning tunneling microscope tips without tip holder

Contact Info

Product

Resources

About