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 Å Be-doped (3×1019 cm−3) In0.53Ga0.47As layer sandwiched between 5000 Å 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.