Silicon‐Modified Rare‐Earth Transitions—A New Route to Near‐ and Mid‐IR Photonics

Abstract

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 ...

A Simple Integratable Silicon Photodetector Covering the Short‐Wave Infrared and Optical Communication Bands at 1.3 and 1.55 μm

“…The alignments of the Ce and Yb levels with the silicon band gap are shown in Figure 2. The alignments have been determined from previously published photoluminescence data [20] of the direct radiative transitions from the conduction band to the RE levels. The long wavelength cutoff, at 5.0 μm, is determined by the lowest energy transitions from the top of the valence band to the ground state levels of the RE.…”

“…REs incorporated in silicon in the trivalent 3+ state. [20,22] The basic mechanism responsible for the subbandgap generated photocurrent, proportional to the excess holes generated in the valence band, in our BEM photodetectors is indicated in Equation ( 1). An absorbed photon excites an electron from the valence band to a level in the RE 3+ ion.…”

Optically modulated magnetic resonance of erbium implanted silicon

“…In rare earth doped semiconductors, the 4 f ground state manifold was previously assumed to lie deep within the valence band 18–20 , based partly on the separation of the 4f-levels of isolated rare earth ions from the vacuum level. We have recently made the first observation of direct optical transitions from the silicon conduction band to internal 4f-levels of implanted Ce, Eu, and Yb, which gave a significant enhancement of emission 21 . We also showed that their 4 f ground state manifolds lie ~1000 cm −1 above the valence band.…”

Metafabrics for Thermoregulation and Energy-Harvesting Applications

“…55 However, the toxicity of the constituent elements and high cost makes application of this alloy limited for on-body platforms. Currently, biodegenerable and low-cost alternatives are being sought, 56 which hold great promise for future thermophotovoltaic applications. One of the advantages of the formalism used in this work is its applicability to the fabric structures embedded in any arbitrary layered media.…”

“…However, the toxicity of the constituent elements and high cost makes application of this alloy limited for on-body platforms. Currently, biodegenerable and low-cost alternatives are being sought, which hold great promise for future thermophotovoltaic applications.…”