Atomic force microscopy study of Si(111) surface morphology and electrical characteristics of Pd/n-Si schottky diodes: effect of cleaning procedures

Abstract

Samples of epitaxially-grown Si(111) doped to 5 × 10 15 P cm -3 were chemically cleaned using various procedures. The surface morphologies and remaining particulate contamination of the samples were investigated using atomic force microscopy (AFM) and the electrical properties of Pd Schottky barrier diodes fabricated on the chemically cleaned surfaces were extracted from current-voltage (I-V) and capacitance-voltage (C-V) measurements. The root-mean-square roughness of the cleaned surfaces varied between 1 ± 0.5 and 16 ± 10 A. The Schottky diodes had ideality factors (n) of 1.02-1.17, currents at a reverse bias of 1 V (I R ) between 4 × 10 -8 and 84 × 10 -8 A and I-V barrier heights (o IV b ) in the range 0.73-0.76 eV. Diodes fabricated on the roughest surfaces had the poorest rectifying properties. Tbe free carrier concentration (N D ) was overestimated by ∼40% when the surface roughness exceeded 10 A. Compared to using a buffered HF solution (NH 4 F-HF, 6:1), native oxide removal with a diluted HF solution (H 2 O-HF, 49:1) resulted in rougher surfaces.