Relationship between dislocation generation, vapor phase supersaturation and growth rate in InP layers obtained by vapour phase epiaxy

The interrelationship between growth conditions, dislocation generation mechanisms and layer growth rate has been studied in InP/InP layers prepared by hydride vapour phase epitaxy. In the present experiments, only the PH3 flow rate was varied, whereas the HCI flow rate was kept constant. Contrary to what is generally believed, even very low growth rates yield a very high dislocation density. The dislocations are generated by the condensation of point defects that are incorporated in supersaturation into the layer during the whole growth sequence. Under higher flow rate conditions, dislocation generation by glide processes seems to prevail. Layers with minimum defect density are obtained for intermediate PH3 flow rates. The influence of either the spiral growth or the two-dimensional nucleation mechanism on the macroscopic layer growth is discussed. A procedure to reduce the morphological defects, termed hillocks, is also suggested.