Spontaneous 2D Accumulation of Charged Be Dopants in GaAs<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi><mml:mtext mathvariant="normal">−</mml:mtext><mml:mi>n</mml:mi></mml:math>Superlattices

The electrostatic screening of localized electric charges on semiconductor surfaces is investigated quantitatively by statistically analyzing the spatial distribution of thermally formed positively charged anion surface vacancies on GaAs and InP͑110͒ surfaces. Two screening regimes are found: at low vacancy concentrations the vacancy charges are found to be three-dimensionally screened by bulk charge carriers. The corresponding screening length, which increases strongly with decreasing carrier concentration, is best described by the classical bulk screening length evaluated with a surface dielectric constant. With increasing vacancy concentration at given bulk carrier concentration, a three-to two-dimensional screening transition occurs. At high vacancy concentrations, the screening is found to be governed by charge carriers located in a two-dimensional surface vacancy defect band, which is partially filled due to the vacancy-induced surface band bending.

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“…In the present case the two dimensionality of the screening is due to the surface and independent of special ordering effects of bulk dopant. 49 …”

Section: The Dependence Of the Screening Length On The Carrier Conmentioning

confidence: 99%

Three- to two-dimensional transition in electrostatic screening of point charges at semiconductor surfaces studied by scanning tunneling microscopy

2009

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“…Thus bulk properties become accessible with the STM. This opens the door to do dopant profiling of heterostructures with atomic precision [91]. Studies performed during this thesis show that the STM catches up features originating from acceptors that are buried deeper than 14 monolayers under the surface.…”

Section: Dopant Induced Anisotropic Conductivity 62mentioning

confidence: 99%

“…Most studies of diode devices are carried out on p-n superlattices because they are easily addressed with the STM. In these systems the dopant distribution and interface roughness have been studied with high resolution [89][90][91]. The influence of the STM tip on the diode field in lightly doped diode superlattices has been reported [92].…”

mentioning

confidence: 99%