Determination of the Gibbs free energy of formation of Ga vacancies in GaAs by positron annihilation

Gebauer, J.; Lausmann, M.; Redmann, F.; Krause‐Rehberg, R.; Leipner, Hartmut S.; Weber, E. R.; Ebert, Ph.

doi:10.1103/physrevb.67.235207

Cited by 41 publications

(46 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…16 Despite considerable theoretical and experimental studies, the charge state of a Ga vacancy is still unclarified; thus, it is an issue in this case. Theoretical calculations 17 and a recent positron annihilation experiment 18 predict the charge of a Ga vacancy as −3e, while diffusion experiments support the values for the −2e ͑Ref. 19͒ and −1e ͑Ref.…”

mentioning

confidence: 99%

Probing nanoscale potential modulation by defect-induced gap states on GaAs(110) with light-modulated scanning tunneling spectroscopy

Yoshida

Kanitani

Takeuchi

et al. 2008

Applied Physics Letters

View full text Add to dashboard Cite

We investigated charged defects on an n-GaAs͑110͒ surface using light-modulated scanning tunneling spectroscopy. Tunneling via a single defect-induced gap state under photoillumination was observed for the isolated atomic defects. Screened Coulomb potentials induced around a charged Ga vacancy and a step edge were visualized, for the first time, with a nanometer spatial resolution. Furthermore, the charge states of the individual defects were determined on the atomic level.

show abstract

mentioning

confidence: 99%

Probing nanoscale potential modulation by defect-induced gap states on GaAs(110) with light-modulated scanning tunneling spectroscopy

Yoshida

Kanitani

Takeuchi

et al. 2008

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…Although the diffusion model and the experimental Fermi level dependence used in different experiments [1,2] are the same, conclusions about the dominant charge state of V Ga are contradictory. This contradiction can therefore be due to experimental errors or the additional assumptions about the temperature dependence of the ionization levels used in the experimental fits.…”

Section: Analysis Of the Experimental Resultsmentioning

confidence: 99%

“…We show that, in spite of well known LDA limitations, apparently conflicting data coming from two experiments performed under different conditions [1,2] are well fitted. This satisfactory fit is obtained for both experimental data by using the same set of inputs like the concentration model, the Fermi level effect and the computed temperature dependence of F q1/q2 .…”

Section: Introductionmentioning

confidence: 95%

“…While experiments have deduced a preferred charge state ranging from −1 and −2 [1] to −3 [2,3] under N-type or intrinsic conditions, most (zero temperature) ab-initio calculations favor the −3 charge state for V Ga , see Ref. [4,5,6,7,8,9,10,11,12,13,14].…”

Section: Introductionmentioning

confidence: 99%

“…These entropic contributions can therefore alter the charge of the dominant species as calculated at T = 0, leading to a strong competition between the charge states. Moreover, the separate ionization energy for each state is not directly accessible experimentally; only the sum over the ionization free energies can be obtained by fitting the experimental data over a range of temperatures, using a number of assumptions typically inspired from ab-initio data [2,3] or set as free parameters in the fit [1].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Thermally activated charge reversibility of gallium vacancies in GaAs

El-Mellouhi

Mousseau

2006

Journal of Applied Physics

View full text Add to dashboard Cite

The dominant charge state for the Ga vacancy in GaAs has been the subject of a long debate, with experiments proposing −1, −2 or −3 as the best answer. We revisit this problem using ab initio calculations to compute the effects of temperature on the Gibbs free energy of formation, and we find that the thermal dependence of the Fermi level and of the ionization levels lead to a reversal of the preferred charge state as the temperature increases. Calculating the concentrations of gallium vacancies based on these results, we reproduce two conflicting experimental measurements, showing that these can be understood from a single set of coherent LDA results when thermal effects are included.

show abstract