1986 wileyonlinelibrary.com devices using alternative direct band gap semiconductors. This hybridization is highly undesirable, seriously violating the paramount technological and cost advantages inherent in silicon integration that has driven its exponential growth. The ultimate vision of silicon integration is a totally single silicon solution incorporating both electronic and photonic functions. Here we report a novel phenomenon-siliconmodifi ed rare-earth (RE) transitions-and demonstrate light emitting diodes (LEDs) and mid-IR photodetectors. Universally, luminescence from RE-doped semiconductors has shown only the expected characteristic intrinsic transitions; consequently emission from REs with transitions greater than the semiconductor band gap energy should not occur. Europium, ytterbium, and cerium have their lowest energy transitions well above the band gap energy of silicon. Remarkably, we see photoluminescence (PL) and electroluminescence (EL) due to Eu, Yb, and Ce in silicon but dramatically redshifted in wavelength and strikingly enhanced in intensity by up to 900 times compared with conventional RE-doped silicon LEDs. These results refute previous thinking on the interaction of REs with semiconductors and offer a promising route to effi cient, fully silicon-based, optoelectronic devices across the near-and mid-IR.Silicon photonics has seen rapid advances [1][2][3][4][5][6][7][8][9][10][11][12] and the technology is seen not just as required for next-generation computers but also as a vehicle for a wide range of other high value and important, societal, environmental, security, and health applications, such as greenhouse gas and explosive residue sensing, and fast medical diagnostics. [ 13 ] REs elements in silicon have long been considered promising for optical sources, and more recently for quantum technologies. [ 14 ] The partially fi lled inner 4 f -shell gives sharp internal transitions highly insensitive to crystal host and temperature and many of the transitions have intrinsic gain and support lasing. However, because the transitions are internal to the RE they have not been seen so far as a particularly promising route to photodetectors.Light emission at 1.54 µm due to Er ions in III-V and Si has been extensively investigated and light emitting devices successfully demonstrated although with limited effi ciency. [15][16][17][18][19][20][21] PL and EL from silicon and III-V semiconductors incorporating the RE thulium have also been achieved-transitions between the Tm 3+ lowest excited states and the ground state lead to emissions around 0.8, 1.2, and 2 µm. [22][23][24] Both Er and Tm in silicon, and indeed all others RE reported in silicon Silicon-Modifi ed Rare-Earth Transitions-A New Route to Near-and Mid-IR Photonics Manon A. Lourenço , * Mark A. Hughes , Khue T. Lai , Imran M. Sofi , Willy Ludurczak , Lewis Wong , Russell M. Gwilliam , and Kevin P. Homewood Silicon underpins microelectronics but lacks the photonic capability needed for next-generation systems and currently relies on ...

We report on photoluminescence in the 1.3 and 1.7 μm spectral ranges in silicon doped with dysprosium. This is attributed to the Dy3+ internal transitions between the second Dy3+ excited state and the ground state, and between the third Dy3+ excited state and the ground state. Luminescence is achieved by Dy implantation into Si substrates codoped with boron, to form dislocation loops, and show a strong dependence on fabrication process. The spectra consist of several sharp lines with the strongest emission at 1736 nm, observed up to 200 K. No Dy3+ luminescence is observed in samples without B codoping, showing the paramount importance of dislocation loops to enable the Dy emission.

We report and compare the luminescence, both photo- and electroluminescence, in the near-infrared of a wide range of rare earths (Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm) doped dislocation engineered silicon light emitting devices. The rare earths are introduced using ion implantation into standard Czochralski (CZ) n-type silicon wafers pre-implanted with boron to form both the p–n junction and an engineered dislocation loop array. Rare earth internal transitions are observed in samples co-doped with Dy, Ho, Er, and Tm. We show that for each rare earth optimizing the optical activity depends critically on the rare earth implant parameters and post-implant process conditions. Room temperature operation in the 1.5 and 2.0 µm spectral regions is observed from the internal rare earth transitions in Er and Tm.

This paper presents a new method based on image processing (IP) for the characterization of porous silicon (PS) nanostructures. It was developed using porous silicon layers (PS1 and PS2) having different nanostructures. According to gravimetric measurements, these layers present the same porosity of 45%. First we characterized the PS layers by Barrett‐Joyner‐Halenda (BJH) theory applied to sorption data. Then applying BJH theory, we found that the mean pore diameter of PS1 and PS2 are 4.3 and 5.5 nm respectively. With Brunauer‐Emmet‐Teller (BET) theory, we found that PS1 has a specific area of 330 m2/g, and PS2 has a specific area of 223 m2/g. We obtained images of the PS layer surface by high resolution scanning electronic microscopy (HRSEM). The processing of these images leads to the estimation of mean pore diameter: 5.6 nm and 7.5 nm for PS1 and PS2 respectively, and to the representation of pore size distribution. According to a geometrical model, we estimated the porosity and found 55% and 48% for PS1 and PS2 respectively. The calculation of specific area according to the same model leads to the values of 343 m2/g and 217 m2/g for PS1 and PS2 respectively. The close agreement of results obtained by IP to those obtained by sorption theories shows the validity of our method. Advantages of images processing are discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)