Electrical characterization of alumina layers deposited by evaporation cell on Si and restructured InP substrates

In the fast electronic area, studies on InP metal—insulator—semiconductor (MIS) devices have wide interest. Effectively, InP presents a considerable interest due to its high mobility and large bandgap for high speed MIS devices. However, the InP surface must be treated and well passivated before the deposition of insulator. We show that the InSb buffer layer can reduce the phosphorus atom migration and the defects at the interface. After the elaboration of Al2O3/Si, Al2O3/InP and Al2O3:InSb/InP structures, we have studied and characterized electrically the alumina—semiconductor systems. Thus, a mercury probe was used as a temporary gate contact. In the Al2O3:InSb/InP structure, the electrical C–V characteristics plotted at 1 MHz give, in the depletion region, a more important slope of the curves. The obtained results show clearly the reduction of the defects, dangling bonds and consequently the state density has been decreased by 50% compared to the InP protected by an InSb buffer layer and no treated surfaces. Then, the interfacial state density NSS is evaluated as 4 × 1011 eV−1 cm−2.