Nanoscale dopant-induced dots and potential fluctuations in GaAs

Abstract

We identified p-type nanoscale dopant-induced dots that are formed by fluctuations of the dopant atom distribution in sufficiently thin GaAs p-n multilayers. Their electronic structure and the resulting potential variations were investigated by cross-sectional scanning tunneling microscopy and spectroscopy as a function of the number of dopant atoms within the dot. We find significant changes in the current-voltage characteristics of the dots compared to spatially nonconfined material, due to a reduced ability to screen the tip's electric field. This indicates a limited ability to deplete the dots of free holes arising from the presence of confining potentials surrounding the dopant-induced dots.

Scanning tunneling microscopy on unpinnedGaN(11¯00)surfaces: Invisibility of valence-band states

“…The number of screening electrons at the surface depends then on the conduction-band density of states and not on the doping concentration, in analogy to the hole accumulation in the valence band described for differently p-doped GaAs͑110͒ in Ref. 17. The different screening origin can also be recognized in the depth dependence of the band bending shown in the inset of Fig.…”

Atomic scale images of acceptors in III-V semiconductors

“…The short range fluctuations are due to single dopant atoms or surface impurities and introduce only faint distortions of the uniform potential drop. The long range fluctuations are visible by the slight bending of the contour lines and might originate from dopant clustering effects as previously observed in p-n superlattices [97]. Besides these slight distortions the built-in potential drops very uniformly across the p-i-n interface.…”

Conductance distribution in nanometer-sized semiconductor devices due to dopant statistics

“…1͒. Schottky barrier inhomogeneities, 9 which have been observed at nonepitaxial interfaces, [10][11][12][13] do not play a role here, as they are due to variations in the atomic arrangement at the metal-semiconductor interface itself. The metal-semiconductor interfaces in our devices are perfectly epitaxial and monocrystalline, which is supported by crosssectional transmission electron micrographs of similar structures.…”