Hydrogen induced optically-active defects in silicon photonic nanocavities.

S Boninelli,T F Krauss,L O’Faolain,G Franzò,R Lo Savio,L Vines,A Shakoor,M Galli,F Priolo,P Cardile,B G Svensson

doi:10.1364/oe.22.008843

Abstract

We demonstrate intense room temperature photoluminescence (PL) from optically active hydrogen- related defects incorporated into crystalline silicon. Hydrogen was incorporated into the device layer of a silicon on insulator (SOI) wafer by two methods: hydrogen plasma treatment and ion implantation. The room temperature PL spectra show two broad PL bands centered at 1300 and 1500 nm wavelengths: the first one relates to implanted defects while the other band mainly relates to the plasma treatment. Structural characterization reveals the presence of nanometric platelets and bubbles and we attribute different features of the emission spectrum to the presence of these different kind of defects. The emission is further enhanced by introducing defects into photonic crystal (PhC) nanocavities. Transmission electron microscopy analyses revealed that the isotropicity of plasma treatment causes the formation of a higher defects density around the whole cavity compared to the ion implantation technique, while ion implantation creates a lower density of defects embedded in the Si layer, resulting in a higher PL enhancement. These results further increase the understanding of the nature of optically active hydrogen defects and their relation with the observed photoluminescence, which will ultimately lead to the development of intense and tunable crystalline silicon light sources at room temperature.

Highlights

The aim of achieving higher data processing speeds and bandwidths is the driving force for the research and development of integrated photonic devices that use photons as data carriers
Transmission electron microscopy analyses revealed that the isotropicity of plasma treatment causes the formation of a higher defects density around the whole cavity compared to the ion implantation technique, while ion implantation creates a lower density of defects embedded in the Si layer, resulting in a higher PL enhancement
These results further increase the understanding of the nature of optically active hydrogen defects and their relation with the observed photoluminescence, which will lead to the development of intense and tunable crystalline silicon light sources at room temperature

Summary

Introduction

The aim of achieving higher data processing speeds and bandwidths is the driving force for the research and development of integrated photonic devices that use photons as data carriers. A number of promising approaches have been taken in the past to enhance the Si emission [1,2,3,4,5,6,7,8,9,10,11] None of these combine all the features required from a practical on-chip light source, namely: room temperature operation, electrical injection, sub-bandgap emission, small size, high output power, spectral purity and tunability. We have demonstrated a Si nano light emitting diode (LED) that has all of the features listed above [12], except for the high output power This device is based on the introduction of optically active hydrogen defects in crystalline silicon and Purcell enhancement via a PhC cavity. To further enhance the emission and to bring it up to practical levels, it is necessary to better understand the nature of these defects and the role they play in the emission process, which is a topic of considerable debate [13,14,15,16,17,18,19,20,21,22]

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