Metalorganic chemical vapor deposition and characterization of (Al,Si)O dielectrics for GaN-based devices

Abstract

In this paper, we report on the growth and electrical characterization of (Al,Si)O dielectrics grown by metalorganic chemical vapor deposition (MOCVD) using trimethylaluminum, oxygen, and silane as precursors. The growth rates, refractive indices, and composition of (Al,Si)O films grown on Si(001) were determined from ellipsometry and XPS measurements. Crystallinity and electrical properties of (Al,Si)O films grown in situ on c-plane GaN were characterized using grazing incidence X-ray diffraction and capacitance–voltage with current–voltage measurements, respectively. Si concentration in the films was found to be tunable by varying the trimethylaluminum and/or oxygen precursor flows. The Si incorporation suppressed the formation of crystalline domains, leading to amorphous films that resulted in reduced interfacial trap density, low gate leakage and ultra-low hysteresis in (Al,Si)O/n-GaN MOS-capacitors.