Interface Optimization and Modulation of Leakage Current Conduction Mechanism of Yb2O3/GaSb MOS Capacitors With (NH4)2S Solutions Passivation

In current work, the impact of ammonium sulfide (NH4)2S solution passivation with varied pH value on the Yb2O3/n-GaSb interface has been investigated comparatively. Compared with control samples, the neutral (NH4)2S solution passivation can effectively reduce oxides layer on GaSb surface and gate leakage via X-ray photoelectron spectroscopy (XPS) measurements and electrical characterization. High-low frequency capacitance method was used to evaluate interface-state density ${D}_{{\text {it}}}$ , it was found that capping with Yb2O3 can delay the interface-state generation and the lowest $D_{{\text {it}}}$ value of ${5.18}\times {10} ^{{12}}$ cm−2 eV−1 for Yb2O3/GaSb capacitor with neutral (NH4)2S was achieved. Moreover, the possible leakage current conduction mechanisms for capacitors measured at room temperature and low temperature have also been discussed systematically.