We report the growth of GaAs by laser-assisted molecular beam epitaxy, using As4 and either elemental Ga or triethylgallium (TEG) sources, and a 193 nm ArF excimer laser. Laser irradiation of (Al)GaAs has no effect on the growth rate or Ga-to-Al incorporation, when GaAs substrates and elemental group-III sources are used. When GaAs is grown from TEG, laser irradiation results in a selective-area film growth at temperatures below 450°C, where growth due to pyrolytic decomposition of TEG is very slow. The process is extremely efficient, with roughly unit probability for impinging TEG molecules sticking and being dissociated by laser radiation to form GaAs. From the strong dependence on laser fluence, the growth enhancement process appears to be pyrolytic in nature (due to rapid transient healing by the pulsed laser), and not photolytic. The cross section for photolysis must be at least ten times lower than the gas-phase value (9x10-18cm2). Using either Ga source, laser irradiation improves surface morphology and photoluminescence yields, compared to areas receiving less intense laser radiation.
In growth of GaAs from elemental sources on (Ca, Sr)F2 lattice-matched to GaAs, laser irradiation inhibits growth due to laser-induced thermal desorption of adsorbed Ga atoms, which are relatively weakly bound to (Ca,Sr)F2 compared to GaAs surfaces.