Structure of the Al–GaP(110) and Al–InP(110) interfaces

The Al–GaP(110) and Al–InP(110) interfaces are characterized with low energy electron diffraction and Auger electron spectroscopy. Both interfaces are reactive, i.e., the replacement of the cation by Al is thermodynamically favorable. However, Al evaporated on the room temperature substrates has a high surface mobility and forms metallic islands which leave the atomic structure of the uncovered semiconductor areas unperturbed. Limited Al–substrate reaction can be detected at room temperature. Moderate annealing triggers a large scale Al‐cation replacement reaction and leads to the formation of AlP layers. The crystalline quality of the AlP layers is good for Al on GaP (0.01% lattice mismatch between AlP and InP) and poor for Al on InP (7% lattice mismatch between AlP and InP). The atomic geometry of AlP(110) is analyzed with multiple scattering LEED computation. A best fit structure is obtained which is consistent with the correlation recently obtained between atomic structure and atomic size on (110) semiconductor compound surfaces.