LOW-TEMPERATURE GROWTH OF HEAVILY CARBON-DOPED GAAS BY METALORGANIC MOLECULAR-BEAM EPITAXY WITH ELEMENTAL GALLIUM

In the growth by metalorganic molecular beam epitaxy (MOMBE) of carbon (C)-doped GaAs, elemental gallium (Ga) has been introduced in addition to conventional sources, trimethylgallium (TMG) and As-4. A drastic increase of growth rate was obtained, while a high hole concentration was maintained. A hole concentration of 4x10(20) cm(-3) with the growth rate of 1.1 mu m/h was achieved. Electrical and optical properties of epilayers are comparable to those of C-doped GaAs epilayers grown with conventional sources. Furthermore, it is found that the incorporation rate of monomethylgallium (MMG) into a growing epilayer increases with increasing beam flux of elemental Ga. This is because the decomposition of MMG into Ga is well controlled by the introduced elemental Ga, maintaining a chemical equilibrium of the steady-state decomposition process of TMG at the growing surface.