Investigations of plasma grown native oxides on indium phosphide carried out recently [1,2] have shown that these oxides exhibit properties which are promising to be used in MIS structures on InP, due to their stable composition which includes [InxPyOz]n polyphosphate phase mainly and due to reduced density of interface states (Nss<1011 eV−1 cm−2). It has been shown also that MIS structures with plasma native oxides exhibit C-V characteristics shifted towards positive values of voltage bias. The flat band shift is assigned to a negative charge injected into oxide film during plasma oxidation. The presence of this negative charge in plasma grown native oxides on InP may cause instability of electric properties of MIS structures [2].The aim of this work was to make an attempt to influence upon negative effective oxide charge density by means of hydrogen plasma treatment.

Ellipsometry and XPS investigations of RF plasma grown native oxide and C-V measurements of its interface were performed. Strong dependence of the composition of the plasma grown native oxides and electric properties of MIS structures on the time of plasma treatment has been observed. The greater the content of stable polyphosphate phase of [InxPyOz] is in the native oxide composition, the better parameters of its interface with InP (Nss<1011 cm−2 eV−1 and the hysteresis of C-V characteristics<0.2 V) and the lesser C-V drift after treatment may be achieved. Plasma oxidation results in creating a negative effective oxide charge density.