ELECTRICAL PROPERTIES OF POROUS SILICON PREPARED BY PHOTOCHEMICAL ETCHING

Abstract

In this work, electrical properties of porous silicon (PS) structure fabricated by using the photochemical etching process in HF acid under different etching times was investigated. (111) n-type silicon wafers with two different resistivities (r₁ = 3.25 x 10^-4 Wcm and r₂ = 4.3-5.6 Wcm) were used. The wafers were etched in 40% HF acid by using 100 W quartz tungsten halogen lamp integral with dichroic ellipsoidal mirror for two different etching times (t₁ = 1800 s and t₂ = 5400 s). The current-voltage characteristics for all Al/PS/n-Si/Al structures show a rectifying behavior with different values of ideality factor and barrier height. The forward and reverse current show Schottky-like behavior and the presence of an inflection point in reverse a characteristic is explained by energy band gap difference between porous silicon and crystalline silicon substrates.