Anodic Niobia Column-like 3-D Nanostructures for Semiconductor Devices

Abstract

Two types of anodic niobia (niobium oxide) column-like three-dimensional (3-D) nanostructures were synthesized by anodization in 0.4 mol•dm -3 oxalic acid aqueous solution at 37 V, reanodizing in 1% citric acid aqueous solution up to 300 and 450 V, and chemical etching of magnetron sputter-deposited Al/Nb metal layers. The dependence of the synthesized niobia column-like 3-D nanostructures' morphological properties on formation conditions were defined by scanning electron microscopy. The niobia column-like 3-D nanostructures' electrophysical characteristics were investigated in two measurement schemes. Aluminum layers of 500-nm thickness were used as contact pads. The current-voltage characteristic (I-V) has nonlinear and nonsymmetrical character. The nonsymmetrical I-V reached ~10 V. The breakdown voltages were 80 and 125 V, self-heating begins at voltage direct connection 33 and 60 V, initial resistance at 23 °C was 60 and 120 kΩ, specific resistance to the height of the columns was 87 and 116 Ω•nm -1 , and the calculated temperature coefficient of resistance in the range 20-105 °C appeared to be negative and rather low, -1.39•10 -2 and -1.28•10 -2 K -1 , for the niobia column-like 3-D nanostructures reanodized at 300 and 450 V, respectively.