The influence of dislocation density on electron mobility in InP films on Si

The average electron mobility and dislocation density have been measured as functions of the film thickness in InP films grown on Si substrates by gas-source molecular beam epitaxy. In a region extending about 2 μm from the Si interface, the density of dislocations was found to be very high and clustering of dislocations was observed by transmission electron microscopy. The corresponding mobility was very small. Beyond 2 μm, clustering was not observed, the density of dislocations decreased, and the average mobility increased with increasing film thickness. Thus, the threading dislocations created by the large InP/Si lattice mismatch can significantly degrade the free carrier mobility of the InP film.