Preparation and Characterisation of Metallic Thin Films for Electroluminescent Devices Based on Porous Silicon

Abstract

For porous silicon (PS) electroluminescent (EL) devices, metallisation is a key process. The state of the art of the main preparation methods of thin metallic films used in PS EL devices is described. Experimental results concerning the structural and electrical characterisation of the metal/PS/p-Si structures are also presented. Different materials, like Au, In, Au-In, In-Sn, Al, etc., in a variety of preparation conditions were used as a solid-state contact on the PS layers. The luminescent properties of these structures were checked after metallic layer deposition by exciting the samples with an UV lamp. It is known that the transparency of a thin layer of 15 nm thickness is 60% or lower, finally only the luminescent structures were evaluated. Scanning Force Microscopy was used to investigate the film morphology; from the I-V characteristics of the metal/PS/p-Si structures it was determined: n<3, series resistance <500 n, low values for contact resistance. The structures with low series resistance values, present the EL properties at lower value of the applied voltage, and are indicated for LED on PS type.

Nanoporous silicon matrix used as biomaterial

“…In the last years due to PS biocompatible properties, PS layers were investigated as support for cell adhesion [2], as matrix for drug delivery [3,4] or for bio (optical) sensors [5,6].…”