The effect of wet chemical etching by KOH solution to the contact on the solar-blind Al 0.65 Ga 0.35 N material

Abstract

ABSTRACT Recently, high-Al-content AlGaN alloy systems have attracted increasing attention, and it is urgent and important to achieve excellent Ohmic contacts with low specific contact resistivity, good thermally stability, clear borderline and smooth surface morphology of this alloy systems to optimize the performance of photoelectric devices. In the experiment, we found that surface disordered layer and oxides including native oxide could be removed by boiling KOH solution. The surface status of both samples was evaluated with scanning electron microscope (SEM) and X-ray photoelectron spectra (XPS). For comparison, then A Ti/Al/Ti/Au multilayer was deposited on the samples with and without wet chemical etch ing to observe their electric properties. After annealing, I-Vcharacteristics via Keyley 236 electric analyzer was measured. Ohmic cont acts with the contact specific resistivity of 6.55×10 -4 cm 2 were obtained between treated samples and the multi-metals. However, nonlinear I-V curves indicated that the contact on the untreat ed sample was still the Schottky contact. Key Words: Solar-blind AlGaN material, Ti/Al/Ti/Au, Boiling KOH solution, Schottky and ohmic contact