EFFECTS OF GA AND AS DESORPTION ON THE CHEMICAL BEAM EPITAXY GROWTH OF (001)GAAS AS MEASURED BY REFLECTION HIGH-ENERGY ELECTRON-DIFFRACTION

We have studied the balance between growth and desorption at a (001) G aAs surface in a chemical beam epitaxy chamber using reflection high e nergy electron diffraction. We found the growth rate to be proportiona l to the flux of our precursors tertiarybutylarsine and triethylgalliu m (TEG). The growth rates and desorption rates were found to be nearly constant in large temperature regions. The surface cracking of TEG li mited the growth rate for low temperatures, and the desorption of Ga a nd As limited the high temperature growth rates. For high temperatures we show that through the application of the law of mass action the he at of evaporation for Ga can be determined to be 4.2 +/- 0.2 eV, This is very close to the values measured in molecular beam epitaxy. We thu s conclude that the high temperature behavior is not determined by pre cursor desorption or chemistry and that the hydrogen and other chemica l reaction products do not appreciably alter the GaAs phase diagram at chemical beam epitaxy growth conditions. (C) 1998 American Institute of Physics.