Surface segregation of InGaAs films by the evolution of reflection high-energy electron diffraction patterns

Surface segregation is studied via the evolution of reflection high-energy electron diffraction (RHEED) patterns under different values of As₄ BEP for InGaAs films. When the As₄ BEP is set to be zero, the RHEED pattern keeps a 4×3/(n×3) structure with increasing temperature, and surface segregation takes place until 470 ℃. The RHEED pattern develops into a metal-rich (4×2) structure as temperature increases to 495 ℃. The reason for this is that surface segregation makes the In inside the InGaAs film climb to its surface. With the temperature increasing up to 515 ℃, the RHEED pattern turns into a GaAs(2×4) structure due to In desorption. While the As₄ BEP comes up to a specific value (1.33×10^-4 Pa-1.33×10^-3 Pa), the surface temperature can delay the segregation and desorption. We find that As₄ BEP has a big influence on surface desorption, while surface segregation is more strongly dependent on temperature than surface desorption.