A method and system for authenticating users while conducting an auction via a computer system. The first pillar region is composed of a plurality of first pillar layers of a second conductivity type and a plurality of second pillar layers of the first conductivity type alternately arranged along a first direction. The upstanding elements include stems with proximal ends attached to the thermoplastic backing and distal caps, and each distal cap has an overhanging portion that extends beyond the stem in a first direction.