Monoenergetic positron beam study of Si-doped GaAs epilayers grown by low-pressure metalorganic chemical vapor deposition using tertiarybutylarsine

Abstract

Si-doped GaAs epilayers grown by low-pressure metalorganic chemical vapor deposition (MOCVD) using tertiarybutylarsine (tBAs) were investigated using a slow positron beam. The concentration of Ga vacancies, VGa, generated in GaAs epilayers was increased drastically by heavy Si doping of more than 1019 cm−3, where the deactivation of Si occurred. This result suggests that the deactivation of Si in GaAs is mainly caused by a VGa-related defect, such as a VGa-SiGa complex. The VGa concentration in the samples grown using tBAs was found to be almost the same as that grown using arsine (AsH3). On the other hand, the VGa concentration in MOCVD-grown Si-doped GaAs is lower than that in molecular-beam-epitaxy-grown material for the same Si concentrations. The generation mechanisms of VGa were found to be greatly dependent on the growth and/or doping methods, in addition to the Si doping concentration.

Direct observation of site-specific dopant substitution in Si doped (Al x Ga1− x )2O3 via atom probe tomography

“…Al2O3, respectively) and dopants are interacting with these cationic vacancies [13,16]. Such specific cationic site occupancy of Si and its interaction with cation vacancies would lead to the formation of complex defects such as VGa-SiGa or VAl-SiAl as observed in the case of GaN or GaAs and AlN [13,[15][16][17]. Considering the RDF results showing cationic substitution for x = 0 (Ga2O3) and x = 1.0 (Al2O3) as a reference, we investigated cation (Ga or Al) site substitution by dopant in rest of the alloy composition with 0 < x < 100 in the next part of this paper.…”

Impacts of Si-doping on vacancy complex formation and their influences on deep ultraviolet luminescence dynamics in AlxGa1−xN films and multiple quantum wells grown by metalorganic vapor phase epitaxy

“…43,55,94) In the case of GaAs:Si, such an overcompensation due to heavy doping has been attributed to the formation of second nearest-neighbor defect complexes such as V Ga -Si Ga (Refs. [122][123][124]. By analogy, defect complexes such as -V Si III III were proposed 48) to be the most probable culprits for the compensating DRCs that emit the 2.5 eV band under photoexcitation in the present Al 0.6 Ga 0.4 N:Si films.…”

“…For instance, overcompensation of heavily-doped Si donors on Ga sites (Si Ga ) in GaAs has been attributed to the formation of a defect complex with V Ga , namely V Ga -Si Ga second nearest-neighbor donor-compensating complexes (Refs. [122][123][124]. Accordingly, it is likely that V III -Si III complexes are formed in Al 0.6 Ga 0.4 N:Si.…”

Reduction of point defect density in cubic GaN epilayers on (0 0 1) GaAs substrates using AlxGa1-xN/GaN superlattice underlayer

“…In this energy range, almost all positrons are considered to annihilate in the c-GaN epilayer. The observed increase in S for high E (415 keV) is due to the annihilation of positrons in the GaAs substrate, whose S parameter, S GaAs ; is typically as large as approximately 0.517 even in the defect-free material [28]. Obviously, the characteristic S value in sample B (0.448) is smaller than that in sample A (0.454).…”