XTEM study of phase transition in MeV ion-implanted InP
MeV ion implantation into III-V compound semiconductors has attracted great attention in recent years because of its high potential for 3-dimensional device fabrication technology. However, a thorough understanding of associated physical processes involved is crucial before it can be universally applied. Our study on this subject with InP using cross sectional and high resolution transmission electron microscopy (XTEM, HRTEM) reveals clearly the structural changes occurring during MeV-ion-implantation and subsequent thermal annealing. It has lead to a better understanding of the mechanism of phase transition in InP under MeV ion irradiation.Samples of n-type InP(lOO) single crystalline wafers were implanted with 5 MeV-N-ions in room temperature with doses ranging from 1014 to 1016/cm2. Post-implantation annealing was carried out in a graphite strip heater at 500 C with ambient H2 flow.Fig. 1 shows a typical XTEM view of an implanted sample at a dose of 1 x 1016/cm2. A wide implanted layer is buried at a maximum depth of 4μm with a slightly damaged top surface. The buried layer appears as a highly disordered crystalline structure when the sample was annealed, whereas it is amorphous in an as-implanted sample.