Effect of oxygen on defect states of Al0.4Ga0.6N layers grown by hydride vapor phase epitaxy

Abstract

The defect states and electrical properties of AlxGa1-xN (x = 0.4) grown by hydride vapor phase epitaxy (HVPE) were investigated. To identify the effect of incorporation of elemental O in AlxGa1-xN crystals, HVPE growth of AlxGa1-xN crystals was conducted with and without the flow of O2. The crystal quality and electrical properties of the AlxGa1-xN layer was analyzed by X-ray diffraction and deep level transient spectroscopy (DLTS). Schottky devices for I–V, C–V and DLTS measurement were formed using Ni/Au metal and Ti/Al metallization. Capacitance DLTS spectra showed two types of deep traps of H1 and H2 in Al0.4Ga0.6N grown without oxygen, while H1’ traps were observed in Al0.4Ga0.6N grown with oxygen. All traps were hole-like traps with activation energies of 1.3 eV(H1), 0.59 eV(H2), and 1.2 eV(H1ʹ). These results show that the oxygen atoms can improve the crystal quality and suppress the defect states in AlxGa1-xN crystals.