Native defects and self-diffusion in GaSb
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Citations
Growth of type II strained layer superlattice, bulk InAs and GaSb materials for minority lifetime characterization
Charged point defects in semiconductors
Near Full-Composition-Range High-Quality GaAs1−xSbx Nanowires Grown by Molecular-Beam Epitaxy
Type–II superlattices base visible/extended short–wavelength infrared photodetectors with a bandstructure–engineered photo–generated carrier extractor
Rectifying Single GaAsSb Nanowire Devices Based on Self-Induced Compositional Gradients
References
Isolated arsenic-antisite defect in GaAs and the properties of EL2.
Large disparity between gallium and antimony self-diffusion in gallium antimonide
Tight-binding calculations for the electronic structure of isolated vacancies and impurities in III-V compound semiconductors
Periodic boundary conditions in ab initio calculations. II. Brillouin-zone sampling for aperiodic systems
Photoluminescence of high-quality GaSb grown from Ga- and Sb-rich solutions by liquid-phase epitaxy
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Frequently Asked Questions (16)
Q2. Why is the material assumed to reach a thermal equilibrium state?
Due to the long diffusion times the material is actually assumed to reach a thermal equilibrium state which corresponds to Sb-rich growth conditions at ;700 °C.3
Q3. What is the effect of p-type doping on the formation of Sb defects?
For the Sb defects the formation energies of both vacancies and interstitials would decrease, but their concentration would still be small compared to that of Ga vacancies and interstitials.
Q4. What is the reaction energy for the complex to dissociate?
The reaction energy for the complex to dissociate decreases from 1.0 to 0.25 eV as the Fermi level is moved from the VBM to the CBM.
Q5. What is the effect of p-type doping on the formation of Ga defects?
The authors estimate that an extreme p-type doping would lower the formation energy of the Ga defect by ;0.1–0.3 eV ~at 450 °C! for stoichiometric or Ga-rich growth conditions thus increasing its concentration.
Q6. What is the vacancy mechanism for the diffusion of Sb?
In the case of the Sb diffusion, a high temperature and Sb-rich ambient conditions are found to increase the concentration of Sb interstitials and thereby the Sb self-diffusion.
Q7. How do you solve the atomistic diffusion mechanism?
In order to resolve the actual atomistic diffusion mechanism ~vacancy or interstitial! for both elements, it would be necessary to perform simulations for the diffusivities.
Q8. What are the mechanisms that have been neglected in these calculations?
The other mechanisms, such as the antisite exchange or the collective diffusive mechanisms, have been neglected in these calculations.
Q9. What is the effect of the increase of the GaSb acceptor concentration on the Ferm?
When moving toward Ga-rich conditions the increase of the GaSb acceptor concentration is seen to pull the Fermi level downward from its intrinsic value.
Q10. What is the Fermi level for the VSb defects?
For Ga-rich growth conditions at T5450 °C the Fermi level is at 0.15 eV ~Fig. 2!, which corresponds to the value ;20.3 eV for the reaction energy.
Q11. How do the authors determine the relative concentrations of the defects?
In showing the relative defect concentrations the authors use the temperature 450 °C, which corresponds to the growth temperature of the molecular beam epitaxy ~MBE!
Q12. What is the reaction that is proposed to explain the loss of Sb interstitials?
The recombination of Sb interstitials and Ga vacancies is a reaction which has been proposed to explain the loss of Sb interstitials:2,3SbGa VGa2Sbi .
Q13. What is the general trend for the residual hole concentrations?
3. There is a decrease in the hole concentration when moving from higher to lower temperatures and from Ga-rich to Sbrich conditions.
Q14. What is the entropy of states of the valence and conduction bands?
The effective densities of states of the valence and conduction bands are calculated from the effective masses of electrons and holes.
Q15. What is the entropy difference in the valence?
The entropy differences can be of the order of 3kB ,6 which corresponds to internal energies ;0.2 eV in the temperature range of 400 to 500 °C.
Q16. Why was the recombination of Sb interstitials performed under Ga-?
In contrast, due to the long diffusion times the Sb diffusion experiments performed under Sb-rich ambient conditions were considered to change the sample composition to correspond to Sb-rich growth conditions.