Effects of the growth temperature and As/Ga flux ratio on the incorporation of excess As into low temperature grown GaAs

Abstract

The controlled incorporation of excess As into GaAs grown by molecular beam epitaxy at low growth temperatures (LT-GaAs) is explored. The substrate temperature and the As/Ga flux ratio were systematically varied to investigate the influence of growth parameters on the formation of native defects and structural properties. Near infrared absorption, magnetic circular dichroism of absorption, and slow positron annihilation were applied to determine point defect concentrations of As antisites (AsGa) and Ga vacancies (VGa). Structural properties of as-grown and annealed LT-GaAs layers were investigated by x-ray diffraction and transmission electron microscopy. In a well defined parameter range the lattice expansion of the LT-GaAs layers correlates with the amount of AsGa. The VGa acceptor concentration can quantitatively account for the ionization of the AsGa donors.

Nonstoichiometric Low-Temperature Grown GaAs Nanowires

“…They are known to result from the accretion of arsenic point defects upon annealing, predominantly As interstitials that are much more mobile than As Ga and can thus form precipitates at much lower temperature. 40 As this incorporation of excess of arsenic is directly related to the growth temperature, 41 we suspect that it is caused by an The markers indicate the position where the spectra were acquired on the NWs. For the pure GaAs NWs that do not show any CL signal, a SEM image is also shown.…”

Stoichiometric growth of high Curie temperature heavily alloyed GaMnAs

“…7,8 For a fixed As:Ga flux ratio, As Ga in low-temperature ͑LT͒ GaAs increases exponentially as T sub is decreased below Ϸ300°C. 9,10 Extended defects are prominent below 200°C, leading to polycrystalline films. 11,12 Previously, we developed combinatorial ͑nonrotated͒ growth to continuously vary As:Ga and, therefore As Ga , in GaMnAs films near the paramagnetic/ferromagnetic transition ͑Ϸ1% Mn͒ with T sub = 250°C.…”

Optimization and temperature dependence characteristics of low temperature In0.3Ga0.7As and In0.53Ga0.47As-In0.52Al0.48As semiconductor terahertz photoconductors

“…[1][2][3][4][5] The key reason for this is the formation of point defects in the crystal, which arises from the excess arsenic atoms incorporated during the low temperature growth. 6 The latter results in unique material properties such as very short carrier recombination times and high sheet resistances, which are desirable features for efficient terahertz photoconductors. 7,8 Furthermore, the post growth annealing of these materials results in further re-arrangement of the point defects leading to improvement of the aforementioned properties due to the subsequent formation of As precipitates.…”