Scanning tunneling microscopy and spectroscopy at low temperatures of the (110) surface of Te-doped GaAs single crystals

Depuydt, A.; Haesendonck, C. Van; Maslova, N. S.; Panov, V. I.; Savinov, S. Yu.; Arseev, P. I.

doi:10.1103/physrevb.60.2619

Cited by 37 publications

(29 citation statements)

References 29 publications

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“…In general, the appearance of such dopants in STM images is dependent on whether they are donors or acceptors, and whether their intrinsic electronic states are shallow (∼<50 meV) or deep (∼>50 meV). Shallow donors in GaAs, such as Si [7] and Te [8], are always imaged as isotropic circular protrusions surrounded by a dark halo in low-bias filled-state images, and dark depressions in high-bias filled-state STM images. This has been interpreted as imaging the screened Coulomb potential of the ionized donors [7].…”

Section: Introductionmentioning

confidence: 99%

Investigating individual arsenic dopant atoms in silicon using low-temperature scanning tunnelling microscopy

Sinthiptharakoon

Schofield

Studer

et al. 2013

J. Phys.: Condens. Matter

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We study sub-surface arsenic dopants in a hydrogen terminated Si(001) sample at 77 K, using scanning tunnelling microscopy and spectroscopy. We observe a number of different dopant related features that fall into two classes, which we call As1 and As2. When imaged in occupied states the As1 features appear as anisotropic protrusions superimposed on the silicon surface topography, and have maximum intensities lying along particular crystallographic orientations. In empty-state images the features all exhibit long-range circular protrusions. The images are consistent with buried dopants that are in the electrically neutral (D 0 ) charge state when imaged in filled states, but become positively charged (D + ) through electrostatic ionisation when imaged under empty state conditions, similar to previous observations of acceptors in GaAs. Density functional theory (DFT) calculations predict that As dopants in the third layer of the sample induce two states lying just below the conduction band edge, which hybridize with the surface structure creating features with the surface symmetry consistent with our STM images. The As2 features have the surprising characteristic of appearing as a protrusion in filled state images and an isotropic depression in empty state images, suggesting they are negatively charged at all biases. We discuss the possible origins of this feature.

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Section: Introductionmentioning

confidence: 99%

Investigating individual arsenic dopant atoms in silicon using low-temperature scanning tunnelling microscopy

Sinthiptharakoon

Schofield

Studer

et al. 2013

J. Phys.: Condens. Matter

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“…Charge density oscillations of the nearly free hole gas around charged defects are expected. Those oscillations have been previously reported for electron accumulation layers on n-type semiconductors [74][75][76][77] and first indications of hole charge density oscillations (CDO) on p-GaAs have been observed [78]. In the dI/dV-maps a bright halo of increased conductivity surrounds the two acceptors for bias voltages beginning at 1580 mV.…”

Section: Circular Featuresmentioning

confidence: 83%

“…Charge density oscillations of this hole gas around charged defects are expected. Those oscillations have been previously reported for electron accumulation layers on n-type semiconductors [74][75][76][77]. In literature they are sometimes refered to as Friedel oscillations.…”

Section: 3mentioning

confidence: 91%

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Atomic scale images of acceptors in III-V semiconductors

Loth¹

2008

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“…Indeed, in a recent STM investigation of GaAs doped with 5ϫ10 17 cm Ϫ3 Te, only flat surfaces are reported. 14 In conclusion, Te dopant atoms in high concentrations significantly increase the roughness and step concentrations on cleavage surfaces of GaAs, such that macroscopic curvatures can be observed. The influence of Te dopant atoms on the cleavage process is connected with the lattice superdilation phenomenon.…”

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confidence: 99%

Effect of dopant atoms on the roughness of III–V semiconductor cleavage surfaces

Quadbeck

Ebert

Urban

et al. 2000

Applied Physics Letters

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We demonstrate that the presence of dopant atoms influences the roughness, morphology, and optical mirror properties of III-V semiconductor ͑110͒ cleavage surfaces. High concentrations of Te dopant atoms in GaAs lead to macroscopically curvatured ͑110͒ cleavage surfaces with high step concentrations. This ''glass-like'' fracture behavior is explained by the ''lattice superdilation phenomenon'' induced by high concentrations of Te dopant atoms in GaAs. © 2000 American Institute of Physics. ͓S0003-6951͑00͒02303-2͔Cleavage of III-V compound semiconductors in the zinc blende structure yield nearly perfect and atomically flat ͑110͒ surfaces. Such cleavage surfaces are well suited to be used as mirror planes of optical resonators in III-V semiconductor laser diodes. 1 However, the cleavage of III-V semiconductors is a very delicate process. For example, it has been demonstrated that dynamical instabilities of the fracture process can lead to rough surfaces. 2 Such low quality cleavage surfaces can severely limit the properties of optical resonators in semiconductor lasers and thus reduce the intensity of the laser itself. Therefore the ability to produce perfect cleavage surfaces, and naturally the understanding of the factors influencing the fracture process, is essential for the fabrication of high quality optical resonators.In this letter we demonstrate that the presence of dopant atoms influences the roughness and morphology of III-V semiconductor cleavage surfaces on the atomic as well as macroscopic scale. We show that the lattice superdilation phenomenon' induced by high concentrations of Te dopant atom in GaAs 3 affects the fracture process such that very rough ͑110͒ cleavage surfaces are produced. These surfaces exhibit even a ''glass-like'' fracture on the macroscopic scale making them unusable for mirrors in optical resonators.In order to determine the influence of dopant atoms on the roughness of cleavage surfaces, we investigated the cleavage properties of GaAs, GaP, and InP single crystals doped with Zn, Cd, Si, S, Sn, and Te. Each sample was well oriented along the ͓110͔ direction and we cut two cleavage slots into opposite sides along the oriented long axis. We cleaved the samples using a double wedge technique in ͗001͘ and ͗110͘ directions. Both cleavage directions yield similar results. All other cleavage directions were avoided, in order to exclude any possible influence of the orientation on the resulting surface morphology. The surfaces were investigated on the atomic scale by scanning tunneling microscopy ͑STM͒ and macroscopically by light optical microscopy.On the macroscopic scale typical ͑110͒ cleavage surfaces of III-V semiconductors are mirror-like flat. Sometimes macroscopic cleavage steps occur, but the different macroscopic terraces of the surfaces have all the same orientation and no curvature at all. In contrast to this well known and characteristic picture, surfaces obtained by cleavage of highly Te doped GaAs (5ϫ10 18 cm Ϫ3

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Scanning tunneling microscopy and spectroscopy at low temperatures of the (110) surface of Te-doped GaAs single crystals

Cited by 37 publications

References 29 publications

Investigating individual arsenic dopant atoms in silicon using low-temperature scanning tunnelling microscopy

Investigating individual arsenic dopant atoms in silicon using low-temperature scanning tunnelling microscopy

Atomic scale images of acceptors in III-V semiconductors

Effect of dopant atoms on the roughness of III–V semiconductor cleavage surfaces

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