S. Abedrabbo

Temperature-dependent emissivity of silicon-related materials and structures

The results of an ongoing collaborative project between the New Jersey Institute of Technology (NJIT) and SEMATECH on the temperature-dependent emissivity of silicon-related materials and structures are presented in this study. These results have been acquired using a spectral emissometer. This emissometer consists of a Fourier Transform Infra-Red (FTIR) spectrometer designed specifically to facilitate simultaneous measurements of surface spectral emittance and temperature by using optical techniques over the near- and mid-IR spectral range and temperatures ranging from 300 K to 2000 K. This noncontact, real-time technique has been used to measure radiative properties as a function of temperature and wavelength for a wide range of silicon-related materials and structures. The first results of the temperature and wavelength dependent emissivity and hence refractive index of silicon nitride, in the literature, is presented in this study.

Emissivity measurements and modeling of silicon-related materials: An overview

An overview of the emissivity measurements and modeling of silicon-related materials is presented. The experimental component of this investigation is based on results obtained utilizing spectral emissometry. An analysis of the comparison of the measured data with other similar approaches is made. In particular, the celebrated work of Sato is revisited to understand the implications of his study. Simulations of the temperature and wavelength dependent emissivity of silicon based on the semiempirical MULTIRAD model are presented. The influence of doping concentration, surface roughness, and coatings on the emissivity of silicon, as a function of temperature, is discussed.

Analytical study of thermal annealing behaviour of erbium emission in Er2O3-sol–gel silica films

Room-temperature 1535 nm band photoluminescence in ~126 nm silica films (6 at% doping), produced by spin coating an Er2O3 and tetraethylorthosilicate sol–gel formulation on silicon substrates, was studied as a function of vacuum furnace annealing (500–1050 °C). Emission is strongly enhanced for annealing near 850 °C, which is shown by modelling the temperature dependence as arising from thermally activated removal of hydroxyl ions. Suitability of such a process for silicon-based applications is discussed.

Ion Beam Mixing for Processing of Nanostructure Materials

Ion beam mixing (IBM) has been used to process various nanostructure materials and thin films for applications in microelectronics and optoelectronics. In this paper, a study of alloy formation of Si-Ge, processed at shallow depths followed by oxygen implantation, is presented. The mixture is annealed to form Si-GeO2-Si, wherein the germanium oxide may form alone or as a matrix with the source of excitation. Characterization techniques used in this study include investigations of the structural variations due to argon ion-beam irradiation by Rutherford backscattering (RBS) and shallow defects and deep trapping level states by thermoluminescence (TL) measurements. Fourier transform infrared (FTIR) spectroscopy is used to analyze the thin film/islands of GeO2 formed in the matrix.

Perspectives on emissivity measurements and modeling in silicon

Abstract A spectral emissometer operating in the wavelength range of 1–20 μm and temperature range of 30–900°C has been utilized to simultaneously measure the reflectance, transmittance and emittance of silicon. Interesting differences in the optical properties have been reported due to differences in surface morphology. Quantitative results of the effects of rough side incidence versus smooth side on the optical properties of the same silicon wafer are analyzed in this study. This analysis is based on a standard one-parameter, multiple-reflection model as extended by Vandenabeele and Maex to include effects of a roughened surface. Their modification essentially replaces the usual internal attenuation factor by an enhanced effective attenuation factor to take into account the effects of surface roughness. In the present study, it has been found that this very simple model gives a good account of the optical properties when radiation is incident on the smooth side of the wafer but fails for incidence for the roughside.

Room-temperature silicon band-edge photoluminescence enhanced by spin-coated sol–gel films

Photoluminescence is observed at room temperature from phonon-assisted band-to-band emission in Si (1.067 eV peak) using unpatterned bulk p-type silicon wafer samples that were spin-coated with Er-doped (6 at. %) silica-gel films (0.13 m) and vacuum annealed (strongest emission for ~700 C). Comparative study of annealing behavior indicates two-orders of magnitude efficiency enhancement. Emission from Er +3 ions in the silica film is used to gauge relative emission strengths. Mechanisms for inducing

Radiative properties of SIMOX

The first experimental results of the temperature dependent radiative properties of separation by implantation of oxygen (SIMOX) wafers, in the literature, have been reported in this study. These measurements have been performed in the temperature range of 17 to 800/spl deg/C and wavelength range of 0.8 to 20 /spl mu/m using a spectral emissometer. A modeling approach based on Multi-Rad, a matrix method of representing multi-layers, has been adopted to interpret the experimental data. Operating ranges of wavelength for pyrometry have been suggested for a reliable monitoring of temperature for processing SIMOX wafers.

Ambient erbium luminescence in silicon and silicon-germanium films

Prior studies have shown that photoluminescence from Er3+ impurities in silicon is severely limited at room temperature by non-radiative relaxation and solid solubility; and room temperature emission from Er3+ in oxide-based hosts becomes diminished at high erbium concentrations. This work presents studies of thin films (0.2 micron thick) prepared by vacuum co-evaporation from elemental sources (Er, Si and Si/Ge) followed by vacuum annealing (600 degrees C); materials of this type, which are produced with high Er3+ concentrations, are shown to be capable of yielding strong room-temperature photoluminescence. Alloy films of Si-Er-O and Si-Ge-Er-O, containing (20 +/- 2) at. % Er and incorporating (16 +/- 2) at. % O (introduced via vacuum scavenging reactions), exhibit emission bands with dominant components at 1.51 and 1.54 micron (~0.04-micron overall spectral widths). Results are discussed in terms of Er-O complex formation and effects of local randomness on cooperative inter-Er3+ energy transfer among thermal-broadened and local-field Stark-split 4I13/2 to 4I15/2 transitions. Advantages of scalability and low-cost associated with this method of producing optically active silicon-based materials are discussed.

Emissivtty Studies on Polycrystalline Silicon and a-Si / SiO 2 / Si

Experimental studies of the room temperature emissivity of polysilicon are reported here. These measurements have been performed using a spectral emissometer operating in the wavelength range of 0.8 – 20 μm. The measured optical properties are deconvolved to yield the wavelength dependent refractive indices and extinction coefficient of polysilicon. An in house developed computer program, OPCalc, is deployed to perform these calculations. Experimental results of the temperature dependent emissivity of a-Si / SiO 2 / Si / SiO 2 / a-Si, fabricated on single side polished silicon substrates, in the temperature range of 300 to 1100 K have been reported here. These measurements are performed for a-Si thickness of 2100A. Comparisons of the temperature dependent radiative properties of these structures between the front and the back show that the contribution of surface roughness to emissivity is negligible- The exposure of these a-Si coated structures to high temperatures in open environment has caused these surfaces to oxidize. Interpretations, have been sought by comparisons of the experimental data with those on SiO 2 / Si structures.