Direct determination of exact charge states of surface point defects using scanning tunneling microscopy: As vacancies on GaAs (110)

Chao, Kuo‐Jen; Smith, Arthur R.; Shih, Chih‐Kang

doi:10.1103/physrevb.53.6935

Cited by 54 publications

(36 citation statements)

References 14 publications

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“…Similar results were obtained for As vacancies in GaAs(110) [35,36,44,45] and P vacancies in GaP(110) [44,46]. These calculations predict for all anion vacancies a single positive charge in p-doped and a single negative charge in n-doped surfaces, independent of the material, in agreement with the experimental data of anion vacancies not only in InP but also in GaAs [43,[47][48][49], InP [50,51], and GaP [26] (110) surfaces. Thus there is a qualitative agreement between theory and experiment.…”

Section: Observation Of Surface Vacancies With Atomic Resolutionsupporting

confidence: 80%

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Defects in III-V semiconductor surfaces

Ebert

2002

Applied Physics A: Materials Science & Processing

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Abstract. This work reports the measurement of the nanoscale physical properties of surface vacancies and the extraction of the types and concentrations of dopant atoms and point defects inside compound semiconductors, primarily by crosssectional scanning tunneling microscopy on cleavage surfaces of III-V semiconductors. The results provide the basis to determine the physical mechanisms governing the interactions, the formation, the electronic properties, and the compensation effects of surface as well as bulk point defects and dopant atoms. 71.55.Eq; 73.20.Hb; 68.37.Ef The electrical properties of semiconductors and thus their applicability in electronic devices are to a large degree governed by defects and dopant atoms incorporated during growth and production processes. Although some defects and dopant atoms may be desired to achieve the optimum device properties, other defects may be formed unintentionally and counteract the desired electronic properties. Therefore, considerable research efforts were focussed on determining the nanoscale physics governing the formation of point defects, the incorporation behavior of impurities, and their respective electronic properties. PACS:Unfortunately, a direct experimental access to point defects in semiconductors is very difficult, because most experimental techniques rely on the interpretation of macroscopic data of differently processed crystals or on signals integrated over a large set of usually unknown defects. Conclusions about point defects on the atomic level were necessarily limited. In contrast, cross-sectional scanning tunneling microscopy (STM) allows us to directly image with atomic resolution individual point defects and dopant atoms. Crosssectional scanning tunneling microscopy is based on a simple concept: the defects inside the crystal are exposed by cleavage on a surface and subsequently imaged with atomic resolution using STM. Such images yielded a large variety of atomically resolved data about point defects and dopant * (Fax: +49-2461/61-6444, E-mail: p.ebert@fz-juelich.de) atoms. The results provided not only significant progress in the understanding of the fundamental physics of point defects in compound semiconductor surfaces, but it has even been possible to draw conclusions about properties of defects inside semiconductor crystals and the physics governing these bulk point defects [1].The present paper illustrates using selected examples of the progress we achieved in recent years in determining the physics governing the nano-scale properties of point defects in compound semiconductors and their surfaces. We concentrate, on the one hand, on anion surface vacancies as the purest example for surface defects in cleavage surfaces of III-V semiconductors and demonstrate the determination of the surface vacancies' key properties, such as chargetransition levels, electrical charge states, lattice relaxation, and interactions. On the other hand, it is shown how to extract the physics governing bulk point defects by STM. Particular focus will be on...

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Section: Observation Of Surface Vacancies With Atomic Resolutionsupporting

confidence: 80%

“…3a). Such voltage-dependent elevations and depressions in STM images are the signature of localized electrical charges, which allow a determination of the polarity [42] and the magnitude of the charge [43]. A detailed discussion of the quantitative charge determination [38].…”

Section: Observation Of Surface Vacancies With Atomic Resolutionmentioning

confidence: 99%

Defects in III-V semiconductor surfaces

Ebert

2002

Applied Physics A: Materials Science & Processing

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“…Again, this weakening is very clear in the H ad + images. These differences are not conclusive, and the experimental images themselves do vary somewhat, [45][46][47][48][49][50][51][52][53][54][55][56][57][58] with others looking more like the simulated vacancy images, but it does seem likely that at least some of the reported images are due to H adsorption, not anion evaporation.…”

Section: H Admentioning

confidence: 93%

“…(Indeed, very similar results have recently been obtained for adsorbed hydrogen on cerium dioxide, which looks in STM just like surface oxygen vacancies. 44 ) Here on the III-V (110) surfaces, the only case that looks significantly different is the (rarely considered experimentally [45][46][47][48][49][50][51][52][53][54][55][56][57][58] ) case of H ad − and V C under negative bias (filled states), where H ad − does not look like V C , but does look somewhat like a native (or other) adatom, Fig. 7.…”

Section: H Admentioning

confidence: 99%

“…59), in contrast to the standard simulated images of V A . The interpretation of these STM images was long controversial, since the experiments [45][46][47][48][49][50][51][52][53][54][55][56][57][58] show the vacancies as symmetric, but theoretical studies [59][60][61][62][63][64] always find them to be Jahn-Teller distorted. The accepted explanation 59 is that thermal flipping between two degenerate Jahn-Teller distorted structures averages out to the symmetric simulated STM image shown in the center-right in Fig.…”

Section: H Admentioning

confidence: 99%

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Hydrogen on III-V (110) surfaces: Charge accumulation and STM signatures

et al. 2013

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The behavior of hydrogen on the 110 surfaces of III-V semiconductors is examined using ab initio density functional theory. It is confirmed that adsorbed hydrogen should lead to a charge accumulation layer in the case of InAs, but shown here that it should not do so for other related III-V semiconductors. It is shown that the hydrogen levels due to surface adsorbed hydrogen behave in a material dependent manner related to the ionicity of the material, and hence do not line up in the universal manner reported by others for hydrogen in the bulk of semiconductors and insulators. This fact, combined with the unusually deep point conduction band well of InAs, accounts for the occurrence of an accumulation layer on InAs(110) but not elsewhere. Furthermore, it is shown that adsorbed hydrogen should be extremely hard to distinguish from native defects (particularly vacancies) using scanning tunneling and atomic force microscopy, on both InAs(110) and other III-V (110) surfaces.

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Quasiparticle Calculations for Point Defects on Semiconductor Surfaces

Hedström

Schindlmayr

Scheffler

2002

phys. stat. sol. (b)

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We discuss the implementation of quasiparticle calculations for point defects on semiconductor surfaces and, as a specific example, present an ab initio study of the electronic structure of the As vacancy in the þ1 charge state on the GaAs (110) surface. The structural properties are calculated with the plane-wave pseudopotential method, and the quasiparticle energies are obtained from Hedin's GW approximation. Our calculations show that the 1a 00 vacancy state in the band gap is shifted from 0.06 to 0.65 eV above the valence-band maximum after the self-energy correction to the Kohn-Sham eigenvalues. The GW result is in close agreement with a recent surface photovoltage imaging measurement.

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Direct determination of exact charge states of surface point defects using scanning tunneling microscopy: As vacancies on GaAs (110)

Cited by 54 publications

References 14 publications

Defects in III-V semiconductor surfaces

Defects in III-V semiconductor surfaces

Hydrogen on III-V (110) surfaces: Charge accumulation and STM signatures

Quasiparticle Calculations for Point Defects on Semiconductor Surfaces

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