S. Koumetz

A model for diffusion of beryllium in InGaAs/InP heterostructures

Abstract This study reports on Be diffusion from a Be-doped (3×10 19 cm −3 ) In 0.53 Ga 0.47 As layer sandwiched between undoped InP layers grown by gas source molecular beam epitaxy. To explain the obtained experimental depth profiles, a kick-out model of substitutional interstitial diffusion mechanism, involving neutral Be interstitials for the InGaAs epilayer and singly positively charged Be interstitials for the InP epilayers, is proposed. Using the boundary conditions at the heterojunctions and taking into account the built-in electric field, Fermi level and bulk self-interstitial generation/annihilation effects, we obtained a good agreement between the simulated and experimental data.

Be diffusion in InGaAs layers grown by gas source molecular beam epitaxy

The diffusion of Be from buried Be-doped InGaAs epitaxial layers, grown by gas source molecular beam epitaxy, has been studied for temperatures between 700 and 900°C. A kick-out model, involving neutral Be interstitial species and singly positively charged group III self-interstitials, is proposed for the diffusion mechanism.

Be diffusion in InGaAs, InGaAsP epitaxial layers and across InGaAs/InGaAsP, InGaAs/InP heterointerfaces

Abstract The diffusion of Be during post-growth Rapid Thermal Annealing (RTA) in InGaAs, InGaAsP, InGaAs/InGaAsP and InGaAs/InP epitaxial structures grown by Gas Source Molecular Beam Epitaxy (GSMBE) has been studied. The observed Secondary Ion Mass Spectrometry (SIMS) concentration distributions, obtained for annealing cycles with time durations of 10–240 s and temperatures in the range of 700–900°C for Be doping concentration of 3×10 19 cm −3 , could be explained by kick-out mechanism considering the neutral Be interstitial species and positively charged group-III self-interstitials.

Beryllium diffusion in InGaAs/InGaAsP structures grown by gas source molecular beam epitaxy

A systematic study of Be post-growth diffusion from buried Be-doped InGaAs layers in undoped InGaAsP layers grown by gas source molecular beam epitaxy was carried out. The experimental structures consisted of a 2000 A Be-doped (3×1019 cm−3) In0.53Ga0.47As layer sandwiched between 5000 A undoped In0.73Ga0.27As0.58P0.42 layers. The samples were subjected to rapid thermal annealing in the temperature range from 700 to 900°C with time durations of 10–240 s. Secondary ion mass spectrometry was employed for a quantitative determination of the Be depth profiles. To explain the obtained experimental results, the kick-out model of substitutional–interstitial diffusion mechanism, involving neutral Be interstitial species and positively charged Ga and In self-interstitial species, has been considered. The Be and self-interstitial diffusivities, the rate coefficient of self-interstitial generation or annihilation, the self-interstitial equilibrium concentration, and the intrinsic carrier concentration were obtained for ternary and quaternary layers as functions of temperature.

Simulation of post-growth Be diffusion in InGaAsP grown by GSMBE

Abstract Be diffusion in InGaAsP quaternary alloys lattice matched to InP by gas source molecular beam epitaxy (GSMBE) was studied using Secondary Ion Mass Spectrometry (SIMS). The experimental structures consisted of a 0.2 μm Be-doped 3×10 19 cm −3 In 0.73 Ga 0.27 As 0.58 P 0.42 epilayer sandwiched between two 0.5 μm undoped In 0.73 Ga 0.27 As 0.58 P 0.42 epilayers. The samples were subjected to rapid thermal annealing (RTA) in the temperature range from 700°C to 900°C with time durations of 10–240 s. Be diffusion was simulated, in order to obtain the best agreements with experimental profiles, according to two kick-out models: the first model using neutral Be interstitials and singly positively charged (Ga, In) self-interstitials, and the second model using singly positively charged Be interstitials and doubly positively charged Ga, In self-interstitials. Comparison with experimental data shows that the first kick-out model gives a better description.

Redistribution of Be in InGaAsP layers grown by GSMBE during post-growth annealing

In this work we present results of beryllium diffusion during the post-growth rapid thermal annealing at 700–900°C in InGaAsP layers grown by GSMBE. The experimental structure consist of a 2000 A Be-doped layer (3×1019 cm–3) In0.73Ga0.27As0.58P0.42 layer sandwiched between 5000 A undoped In0.73Ga0.27As0.58P0.42 layers. A kick-out model of the substitutional-interstitial diffusion mechanism, which involves neutral Be interstitial species and positively charged group III self-interstitials, is proposed to explain the observed SIMS depth profiles.