Plasma-assisted epitaxy (PAE) has been applied to grow GaAs and GaSb layers at low substrate temperatures with relatively high growth rate. PAE GaSb layers deposited in hydrogen plasma were found to show much better results than those in argon plasma as indicated by lower carrier concentration, higher Hall mobility and clear edge emission in photoluminescence. Hole concentration and Hall mobility of a non-doped GaSb layer deposited in hydrogen plasma at a substrate temperature of 390°C on GaAs (100) substrate are 6×1016 cm-3 and 620 cm2/V·sec, respectively, which are comparable to those obtained by other methods like MBE, MOCVD, etc., in spite of a lower substrate temperature in PAE. This technology is also considered to be useful in growing highly n+ and p+ GaAs layers for their application to non-alloyed ohmic contacts employed in almost all kinds of GaAs devices or the top layers of p-n junction type GaAs solar cells.