Photoluminescence in the 1.2–1.35
μm range has been observed in silicon substrates incorporating thulium in the trivalent Tm
3+ state and co-doped with boron. The results showed eight sharp lines at ...1211.5, 1231.0, 1250.8, 1269.3, 1283.8, 1290.6, 1311.3 and 1326.0
nm, corresponding to known internal Tm
3+ transitions in the manifold from the
3H
5 to the
3H
6 ground states. The luminescence was strongly dependent on the sample fabrication processes. In this paper we will discuss the influence of Tm implantation parameters and post-implant annealing conditions on the photoluminescence response of silicon doped with Tm
3+.
Stability of nano-scaled Ta/Ti multilayers upon argon ion irradiation Milosavljević, M.; Milinović, V.; Peruško, D. ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
10/2011, Letnik:
269, Številka:
19
Journal Article
Recenzirano
► The effects of argon ion irradiation on Ta/Ti multilayers were investigated. ► Despite of relatively heavy ion irradiation, Ta and Ti layers remain unmixed. ► Individual nanocrystalline layers keep ...the same level of interface planarity. ► Such behavior is assigned to dynamic demixing due to chemical driving forces. ► The results can be interesting towards developing radiation tolerant materials.
The effects of argon ion irradiation on structural changes in Ta/Ti multilayers deposited on Si wafers were investigated. The starting structures consisted of sputter deposited 10 alternate Ta (∼23
nm) and Ti (∼17
nm) layers of a total thickness ∼200
nm. They were irradiated at room temperature with 200
keV Ar
+, to the fluences from 5
×
10
15 to 2
×
10
16
ions/cm
2. The projected ion range was around mid-depth of the multilayered structure, and maximum displacements per atom ∼130. It was found that, despite of the relatively heavy ion irradiation, individual nanocrystalline Ta and Ti layers remain unmixed, keeping the same level of interface planarity. The changes observed in the mostly affected region are increase in lateral dimensions of crystal grains in individual layers, and incorporation of bubbles and defects that cause some stretching of the crystal lattice. Absence of interlayer mixing is assigned to Ta–Ti immiscibility (reaction enthalpy Δ
H
f
=
+2
kJ/mol). It is estimated that up to ∼5
at.% interface mixing induced directly by collision cascades could be compensated by dynamic demixing due to chemical driving forces in the temperature relaxation regime. The results can be interesting towards developing radiation tolerant materials based on multilayered structures.
In this paper, we first introduce and discuss the current state-of-the-art in integrated silicon photonic technology. We argue that the only missing link to the incorporation of this technology into ...mainstream high end silicon chips and systems are the availability of fully integrated silicon light sources and amplifiers. We go onto describe how dislocation engineering can be used to nano-engineer, locally, the strain in optically active silicon devices to enable high operating temperatures. We show how, by combining this approach with the incorporation of rare earths, that have optical levels in the near infra-red below the silicon band-gap, a potential route exists to meet these needs. In particular, we show that the use of erbium, together with dislocation engineering, could provide useful optical emission and gain at the important 1.5
μm wavelength that dominates optical data transfer.
We fabricated a Ti Pd asymmetrically contacted single carbon nanotube (CNT) field-effect transistor (FET) with split-gates. Transfer characteristics can be explained if the Schottky barrier for ...electrons is lower at the Pd contact than it is at the Ti contact. Strong rectification is observed when the gates are unbiased, and the rectification direction can be inverted with the appropriate gate bias. When operated as an FET the device has an on off ratio of 1 × 107. Under illumination, photocurrent can only be observed with opposite split-gate bias. Open circuit voltage (V OC) and short circuit current (I SC) increase with increasing opposite polarity split-gate bias, representing the first demonstration of the modulation of V OC and I SC in an asymmetric contact CNT FET.
This article presents a study of the possibilities of optimising the electroluminescence (EL) efficiency of dislocation-engineered silicon light-emitting diodes (DELEDs). The diodes were produced by ...implantation of boron in n-type (100)Si wafers, at a constant ion energy and fluence, of 30 keV and 1X1015 ions/cm2, respectively. The density and the areal coverage by dislocation loops were varied by applying different annealing times in a rapid thermal processing, from 30 s to 60 min. It is shown that the EL efficiency is directly correlated to the number and areal coverage by the loops. The highest population of loops, ~5X109 /cm2, and an areal coverage of around 50% were achieved for 1--5 min annealing. This loop distribution results in optimal DELEDs, having the highest EL response and the largest increase of EL intensity with operating temperature (80--300 K). The results of this work confirm a previously introduced model of charge-carrier spatial confinement by a local stress induced by the edge of the dislocation loops, preventing carrier diffusion to non-radiative recombination centres and enhancing radiative transitions at the silicon band edge.
We report here on the synthesis of semiconducting amorphous FeSi2 layers by co-sputter deposition of Fe and Si on silicon (100) wafers. The layers were grown to a thickness of 300-400 nm, at various ...substrate temperatures. Structural characterisation has shown that the deposited layers have the FeSi2 stoichiometry and are fully amorphous up to a deposition temperature of 200 DGC. Optical absorption measurements have demonstrated that the amorphous FeSi2 layers have semiconducting properties, with a direct band gap of 0.89-0.90 eV at room temperature (RT). In order to relax the amorphous structure, some samples were irradiated with 200 keV Ar ions. It was found that both an increased deposition temperature and/or ion irradiation induce a higher photo-absorption, which was attributed to establishing a medium range order in the amorphous phase. The applied fabrication routine can be highly efficient for potential applications of this material in large area electronics and for production of solar cells.
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