Enhanced field emission from p-doped black silicon on pillar structures

Abstract

Aligned square arrays of black silicon (b-Si) on top of pillars were fabricated on p-type silicon substrate by a deep-etching step combined with a b-Si process. Two 10×10 arrays with pillar heights of 8 µm and 20 µm and one b-Si reference sample without pillars were investigated. Integral field emission (FE) measurements of the arrays yielded rather low onset-fields between 6.4 V/µm and 13.5 V/µm and field enhancement factors between 430 and 800. The I–V curves showed typical Fowler-Nordheim behavior for low fields, whereas a saturation region was observed at higher fields. The maximum integral current in the saturation region was 8 µA at a field of 20 V/µm. The stability of the emission current was investigated over 3 hours and revealed moderate fluctuations of ± 8% in the saturation region. Voltage scans showed well-aligned FE from nearly all pillars.