Enhancement of effective electron mobility in the channel of InP metal-insulator-semiconductor field-effect transistors

Effective mobility of electrons in the channel of accumulation type InP metal-insulator-semiconductor field-effect transistors has been enhanced by means of reducing the iron concentration in the InP substrate and by lowering the deposition temperature of the gate insulator. The highest effective electron mobility, which has been obtained in this work, was about 4000 cm2/V s at room temperature. This was achieved by using InP wafers doped with Fe, whose concentration was 1.6×1016 cm−3, as the substrate and by depositing phosphorus nitride film as the gate insulator at 350 °C. The results are attributed to a less density of scattering centers, both in the InP substrates due to the smaller concentration of Fe and at the interface between the phosphorus nitride film and the InP substrate due to the smaller density of defects, induced during the deposition process at a lower temperature.