[15a-513-1~8] 13.6 Semiconductor English Session

▲ [15a-513-8] Grown-in Beryllium Diffusion in Indium Gallium Arsenide: An ab initio,
Continuum Theory and Kinetic Monte Carlo Study

〇Sergei Manzhos¹, Wenyan Liu², Mahasin Alam Sk¹, Ignacio Martin-Bragado³, Francis Benistant⁴, Siew Ann Cheong² (1.Natl Univ Singapore, 2.Nanyang Tech Univ, 3.IMDEA, 4.Globalfounderies)

Keywords:InGaAs, doping, diffusion

There is significant research interest in InGaAs as a promising candidate for future generation CMOS devices. Beryllium is an attractive p type dopant due to a high activation ratio and the existence of well-developed and controllable doping methods. Be diffusion in InGaAs is extremely fast. Its anomalous dopant diffusion behavior is a roadblock in utilizing InGaAs for scaled-down electronic devices. Specifically, existing models are not able to explain available experimental data on beryllium diffusion consistently. The mechanism that governs Be diffusion was widely assumed to be the kick-out mechanism. Later, the Frank-Turnbull (dissociative) mechanism was proposed to be important. While previous works were able to match experimental data, the parameters used in these models, such as the reaction energy and diffusion parameters, were not extracted from or validated by other independent self-diffusion and in-diffusion experiments or ab initio calculations. These models also treated In and Ga as effectively the same kind of atom.
We propose a comprehensive model, taking self-interstitial migration and Be interaction with Ga and In into account. Density functional theory (DFT) calculations are first used to calculate the energy parameters and charge states of possible diffusion mechanisms. Based on the DFT results, continuum modeling and kinetic Monte Carlo simulations are then performed. The model is able to reproduce experimental Be concentration proles. We are able to reproduce experimental data under different annealing temperatures and durations in a consistent way. Our results suggest that the Frank-Turnbull mechanism is not likely, instead, kick-out reactions are the dominant mechanism. Due to a large reaction energy difference, the Ga interstitial and the In interstitial play different roles in the kick-out reactions, contrary to what is usually assumed. The DFT calculations also suggest that the influence of As on Be diffusion may not be negligible.