Raman spectroscopic assessment of Si and Be local vibrational modes in GaAs layers grown by molecular beam epitaxy

A Raman study of heavily Si- and Be-doped GaAs grown by molecular beam epitaxy is discussed. Both impurities give rise to local vibrational modes (LVM) which can be observed in Raman spectroscopy for impurity concentrations exceeding ~2×10¹⁸ cm^-3. Compared to absorption spectroscopy, which is the `classical´ technique to study LVMs in relatively thick (≥1 μm) layers, Raman spectroscopy permits analysis of the incorporation of both dopants in thin (≥10 nm) as-grown GaAs layers.