Effect of substrate temperature on molecular beam epitaxial GaAs growth using As2

The effect of substrate temperature on Si incorporation, electron mobility, growth rate, and surface morphology in GaAs films grown by molecular beam epitaxy using a dimeric arsenic (As2) source has been investigated. As the substrate temperature was raised from 570 to 700 °C, the measured carrier concentration and electron mobility were observed to decrease while the Si and C acceptor peaks detected in low‐temperature photoluminescence measurements were seen to increase, indicating increased carrier compensation with increasing substrate temperature. The epitaxial GaAs growth rate was nearly independent of substrate temperature with the use of As2, in contrast with the observed reduction in growth rate for substrate temperatures ≫640 °C when the tetrameric arsenic (As4) is employed. Surface defects on films grown with As2 were found generally to increase with substrate temperature; however, at 680 °C defect densities could be reduced tenfold or more by increasing the arsenic overpressure. No such decrease was observed in films grown with As4.