Time-resolved measurements of the photoluminescence of Cu-quenched porous silicon

Abstract

We have performed time-resolved photoluminescence measurements in the submicrosecond to microsecond time regime on porous silicon samples under several diffusion-based chemical treatments with copper ion solutions that produce varying crystallite surface conditions. Our results for short emission wavelengths emanating from high lying states indicate that Cu acts largely on the population process commencing from the top of the well at short relaxation time scales immediately after excitation, and to less extent on the radiating states in the microsecond regime.

Sensitive detection of copper ions via ion-responsive fluorescence quenching of engineered porous silicon nanoparticles

“…1 ). The UDA-PS NPs show quenching efficiencies between 3% and 20%, depending on the type of ion, of which Fe 2+ ions show a particularly high quenching efficiency of 40., It should be noted that other copper ion sensing NPs, such as carbon dots 22 23 24 25 , also demonstrate a strong selectivity of fluorescence quenching by copper and other positive ions (i.e. Fe 2+ ); the complexation of NPs with organic molecules specific for copper ions 25 (e.g.…”

“…N-type, As-doped silicon wafers with a diameter of 500 mm (2 in), an <111> orientation, and resistivity of 0.001–0.01 Ω·cm were used in this study. The Si wafers were electrochemically etched in an HF–H 2 O–ethyl-alcohol (1:1:4 v/v) mixture after lateral etching, following a procedure reported elsewhere 24 25 . In brief, anodic etching was performed in a polycarbonate cell with dimensions of 150 × 60 × 50 mm.…”

“…Various methods have been reported for the synthesis of such PS NPs 9 10 11 12 13 14 15 , including their fabrication from Si wafers via electrochemical wet etching 19 as previously demonstrated by our group. Interestingly, previous studies on PS NPs report that oxide-terminated silicon NPs often experience PL-quenching under a variety of conditions 20 21 22 , in which Cu 2+ can dramatically reduce the quantum efficiency of porous silicon by capturing excited carriers and interrupting radiative recombination processes 23 24 . In particular, the fluorescence of alkyl-terminated PS NPs (APS NPs) exhibit a linear relationship with the concentration of Cu ions, in which bare PS NPs do not show significant PL-quenching in the presence of Cu ions 23 25 .…”

Porous Silicon on Insulator Technology

“…With stable physical and optical features of asanodized porous silicon, several techniques have been developed the most effective methods is the oxidation by formation of SiO 2 layer on PS cores [4]. Various oxidation approaches, such as chemical oxidation, anodic oxidation [5], conventional furnace oxidation [6], thermal oxidation [7,8] and aging oxidation [9], are used to generate a more stable O-passivated surface to replace the unstable H-passivated surface. Furthermore, those oxidation ways can improve efficiency of light emission [10,11].…”

Photoluminescence of Erbium, Zinc and Copper Doped Porous Silicon and a Phenomenological Model for the Metal Electrodeposition

“…Contrary to Er atoms, which are considered as carrier trap centers and luminescence centers in PS [9], the main effect of copper is to capture excited carriers immediately after excitation and before relaxation to the low-lying radiating states [10]. Therefore, doping of Cu into PS favors nonradiative recombination and leads to quenching of the PL.…”