A rate equation model is employed to investigate surface dynamic processes such as In desorption and In incorporation in the MBE growth of InGaAs. Results of temporal variation of desorption rate when the Ga or In flux is turned on or off are compared with the experimental results and the agreement is very good. In both experimental and our simulation results, In desorption increases by increasing substrate temperature and increasing over pressure ratio. The physical reasons for the observations are presented and discussed. The desorption process is observed to have two independent components, one arising from the physisorbed layer of In and the other from the surface of the crystal. The activation energy for these processes for an isolated In adatom are 0.18 and 2.6 eV, respectively. It is observed that surface mechanisms such as segregation and incorporation control the growth and composition profiles. (C) 2002 Elsevier Science B.V. All rights reserved.