Surface Reconstructions of InP (001)

    The surface structures of InP (001) are completely different from their counterpart on GaAs (001).  Several STM images published in PRL and PRB are shown below.



     The freshly MOCVD grown InP (001) thin film is covered with P ad-dimers, alkyl groups and hydrogen atoms.  The phosphorous ad-dimers form a c(2x2)/p(2x2) structure on the surface.



     Slightly annealing the c(2x2)/p(2x2) surface in vacuum at 300 oC results desorption of the P, CHx, and H adsorbates.  The surface becomes (2x1), which is covered with a complete layer of P dimers.  Electron counting reveals that there are only three dangling electrons associated with each dimer.  The honeycomb structure highlighted in the image is a higher ordered c(4x2) reconstructions 


InP s-(2x4)

    Further annealing of (2x1) surface at 400 oC for 30 min leads to desorption of phosphorous from the surface.  The surface becomes an indium-rich s-(2x4). For each (2x4) unit cell, there is one phosphorous dimer in the top layer and four indium dimer in the second layers

InP d-(2x4)

   s (2x4) surface can be further converted to d (2x4) by replacing the P-P dimer with a In-P mixing dimer.  This surface shown on the left was obtained by annealing the InP crystal at 500 oC.  The triangular spots highlighted in the image is corresponding to one P dangling bond and two In-In backbonds.


Copyright 1996-2007, R. F. Hicks, Semiconductor Material Chemistry and Plasma Processing Laboratory, University of California, Los Angeles.

For information, please contact Professor Robert F. Hicks
Last Modified May 21, 2007 05:58 PM