Native defects and self-diffusion in GaSb

Abstract

The native defects in GaSb have been studied with first-principles total-energy calculations. We report the structures and the formation energies of the stable defects and estimate the defect concentrations under different growth conditions. The most important native defect is the Ga Sb antisite, which acts as an acceptor. The other important defects are the acceptor-type Ga vacancy and the donor-type Ga interstitial. The Sb vacancies and interstitials are found to have much higher formation energies. A metastable state is observed for the Sb Ga antisite. The significantly larger concentrations of the Ga vacancies and interstitials compared to the corresponding Sb defects is in accordance with the asymmetric self-diffusion behavior in GaSb. The data supports the next-nearest-neighbor model for the self-diffusion, in which the migration occurs independently in the different sublattices. Self-diffusion is dominated by moving Ga atoms.

Concentration of intrinsic defects and self-diffusion in GaSb

“…9,10 The density functional theory ͑DFT͒ study of Hakala et al 9 was consistent with the conclusions of Bracht et al 6,7 in that the dominant native defects are the Ga interstitial ͑Ga i ͒, the Ga vacancy ͑V Ga ͒, and Ga antisite ͑Ga Sb ͒.…”

“…Under intrinsic conditions e is approximated by one-half of the energy of the band gap ͑E g ͒. The temperature ͑T͒ dependence of the band gap is given by 32 Table I represents the Hakala et al 9 formation energies of native defects in GaSb for Ga-rich ͑⌬ = ⌬H f = 0.43 eV͒ and Sb-rich ͑⌬ = ⌬H f = −0.43 eV͒ conditions under intrinsic conditions ͑ e = E g / 2͒. To quantify the temperature dependence of the concentration of isolated defects ͓D͔, we used the relation ͓D͔ = N s exp͑−E f / k B T͒, where N s is the density of sublattice sites ͑1.75ϫ 10 22 cm −3 ͒, E f is the formation energy of the defect, and k B is Boltzmann's constant.…”

Photoluminescence studies on Al and Ga interdiffusion across (Al,Ga)Sb∕GaSb quantum well interfaces

“…3͑a͒, the peak at lower energy, ϳ 1660 nm, has been attributed to the Ga Sb acceptor to conduction-band transition. 28,29 In Fig. 3͑b͒, the peaks at lower energy, ϳ 1551 and 1598 nm, are attributed to substrate band-to-band recombination ͑1551 nm͒ and to transitions of free electrons to neutral native acceptors ͑1598 nm͒.…”

Acceptors in undoped GaSb; the role of vacancy defects

“…The material can be lattice matched with III-V compounds to form a substrate material for various optical communication devices. Furthermore, GaSb has high electron mobility and saturation velocity, which can be utilized in high electron mobility transistors [2]. To some extent, GaSb is a well known compound.…”

“…This makes GaSb useful in the fabrication of infrared detectors and sources. GaSb has a melting point of approximately 700 K [1,2,3,4]. The material can be lattice matched with III-V compounds to form a substrate material for various optical communication devices.…”