bluuebunny/crossref_metadata_2025 huggingface dataset:
A Self-Interstitial Related Model for the Formation of Thermal Donors in Silicon
Authors: Mathiot D.
Published: March 2011

A new kinetic model is presented for the formation of thermal donors in silicon. This model is based on the aggregation of the self-interstitials generated by oxygen precipitation, on preexisting oxygen related nuclei.
Tem Study of Metal Impurity Precipitates in the Surface Regions of Silicon Wafers
Authors: Seibt M. , Graff K.
Published: March 2011

The precipitation behaviour of the transition metals Co, Ni, Cu and Pd has been studied by means of conventional and high - resolution electron microscopy. Special experimental conditions for specimen preparation were chosen, which lead to the formation of haze. These conditions were the same for all metals. Therefore, a direct comparison of the respective precipitation phenomena was possible. Co and Ni were found to precipitate as Si - rich silicide particles exhibiting various morphologies attributed to different stages of particle growth and ripening. It is shown that the generation of Si- self - interstitials (and vacancies) plays a minor role in the preci-pitate formation. On the other hand Cu and Pd precipitate as metal - rich silicide particles. They form star - like colonies consisting of small particles and extended extrinsic edge - type dislocation loops. The precipitation behaviour of these two met-als is governed by the generation of Si - self - interstitials due to the large misfit of the metal - rich silicide particles.
Hydrogen-Induced Defects in Silicon by CF4/x% H2 (0≤x≤ 100) RIE and H2 Plasma
Authors: Jeng Shwu-Jen , Oehrlein Gottlieb S. , Scilla Gerald J.
Published: March 2011

The extended defects induced by hydrogen diffusion in silicon during the process of (1) CF4/x% H2(0≤x≤100) reactive ion etching, or (2) hydrogenation in H2 plasma, or (3) passivation of boron acceptors in H2 plasma, are studied by high resolution electron microscopy and secondary ion mass spectrometry. In reactive ion etched Si, a higher density of {111} planar defects are produced as the concentration of H2 in the etching gas and/or the overetch time is increased. The Si surface appears rough after reactive ion etching. Similar {111} planar defects are also found in Si after a H2 plasma treatment at 200°C for 3 hours, while the Si surface remains smooth. Boron im-plantation (30keV, 1015 at/cm2) and furnace annealing (1000°C, 30 min) processes are found to introduce stacking faults and perfect dislocation loops into silicon wafers. After subsequent exposure of boron implanted Si to a H2 plasma (200°C, 3 hours), microprecipitates associated with dislocation loops are observed.

These results indicate that the apparent surface roughness (top 30 Å layer) in reac-tive ion etched Si is caused by energetic ion bombardment (∼500 eV). However, the {111} planar defects in CF4/x% H2(x>40%) reactive ion etched Si and the {111} planar defects and microprecipitates in H2 plasma treated Si are induced by the super-saturation of hydrogen diffused into Si during the plasma treatment process.
Localization of Hydrogen in B and in Doped Silicon by ion Channeling and PAC
Authors: Wichert Th. , Skudlik H. , Carstanjen H. -D. , Enders T. , Deicher M. , Grübel G. , Keller R. , Song L. , Stutzmann M.
Published: March 2011

The lattice site of H/D atoms in silicon doped with B and 111In atoms is investigated using the ion channeling and perturbed γγ angular correlation (PAC) technique. The results indicate that at 295 K the antibonding site is occupied by H/D and that this site is easily transformed into a near tetrahedral site under the influence of an analyzing ion beam. Based on PAC results, the population of a second site, possibly a bond-center site, is expected at low temperatures.
Hydrogen Injection Into P-Type Silicon By Chemical Etching
Authors: Tavendale A. J. , Williams A. A. , Pearton S. J.
Published: March 2011

Hydrogen injection with B acceptor neutralization in p-type Si etched in HNOs and HF acid mixtures has been confirmed by isotopic [D] substitution and secondary ion mass spectrometry [SIMS] profiling. Quantitative measurements of the near-surface Injected hydrogen were made following field-aided, in-bulk transport [H+ drift] in reverse-bias annealed Schottky diodes from etched, B-doped Si. Chemical-etch injection is found to be self limiting with neutralization observed over a depth which is characteristic of the base material acceptor concentration and in the range 6–8 extrinsic Debye lengths, indicating that holes are essential in the injection mechanism. An effective diffusivity for hydrogen in etched p-Si of ∼ 2 × 10−9 cm2 s−1 was measured [300 K], considerably higher than previously reported.
Optically Detected Magnetic Resonance of Zinc Interstitials and Frenkel Pairs in ZnSe
Authors: Watkins G. D. , Rong F. , Barry W. A. , Donegan J. F.
Published: March 2011

Optical detection of magnetic resonance (ODMR) is reported for ZnSe irradiated by 2.5 MeV electrons in situ at 4.2K. Interstitial zinc atoms are detected in both isolated form and paired with zinc vacancies (Frenkel pairs) of many resolved discrete separations. The isolated interstitial produces a deep second donor state (+/++) at ∼Ec -0.8 eV and its activation energy for migration is estimated to be ∼0.6–0.7 eV. The Frenkel pairs give rise to efficient localized donor-acceptor recombination luminescence and the exchange interactions between the electron and hole on the two partners are measured directly by ODMR.
Direct Experimental Evidence for Monosilane Formation Even after High Temperature Proton Implantation of Crystalline Silicon
Authors: Tatarkiewicz Jakub , Król Andrzej
Published: March 2011

The paper proves experimentally that no multisilanes are formed even after high temperature proton implantation of crystalline silicon.
Hydrogen in III–V Semiconductors
Authors: Dautremont–Smith W. C.
Published: March 2011

The reversible introduction of atomic hydrogen into III–V semiconductors reduces the active concentrations of shallow donor and acceptor levels, as well as a variety of deep levels. Dissociation of the hydrogen-containing complexes by thermal annealing can restore the original active concentrations, and aid in the characterization of the complexes involved. Hydrogen is in-diffused at temperatures typically in the 150 to 300°C range, most simply from an H2 plasma.

In GaAs, the III–V compound which has been subjected to the most hydrogenation studies, carrier concentrations are reduced (by up to many orders of magnitude) in both n- and p-type material. Hydrogen diffusion depths are dependent on dopant concentration, but for similar doping levels, diffusion is always deeper into p-type GaAs. In addition, the type of plasma exposure strongly influences the depth of H diffusion, with low frequency, direct exposure producing the greatest penetration depth. A variety of deep level defects in bulk material (including EL2) and in MBE-grown layers can be passivated, and partial passivation of interface-related defects in GaAs-on-Si has been demonstrated. Reactivation kinetics are dependent on the nature of the dopant or defect, with the passivation of p-GaAs being less stable than that of n-GaAs. Recent infra-red absorption studies have confirmed the formation of a donor-hydrogen complex in n-GaAs, in contrast to an As-H complex in p-GaAs. In GaAIAs, acceptors, donors, and the DX center have been passivated. In some cases, the defect passivation has greater thermal stability than that of the shallow levels, a property of potential benefit. Recently demonstrated applications of hydrogenation include an MBE GaAs MESFET with a hydrogenated channel, and a GaAs/GaAIAs double heterostructure laser with current guiding provided by resistive hydrogenated regions.
Photoluminescence Detection of Shallow Impurity Neutralization in Iii-V Compound Semiconductors
Authors: Weber Jörg , Singh Mandeep
Published: March 2011

We studied the low-temperature photoluminescence (PL) of several III–V compound semiconductors before and after hydrogen-plasma treatment. Drastic intensity changes of the bound exciton luminescence after hydrogen plasma treatments indicate a neutralization of impurities by the atomic hydrogen. In GaP, neutralization of the sulfur donor as well as the acceptors (C, Zn, Cd) is observed. The intense luminescence of the exciton bound to isoelectronic N in GaP is fully quenched by hydrogen plasma treatment.
Intrinsic Defects in GaAs - the Case of El2
Authors: Von Bardeleben H. J. , Stievemard D.
Published: March 2011

The arsenic antisite-arsenic interstitial pair model for the stable configuration of the EL2 defect in GaAs has stimulated new experimental and theoretical studies, the results of which lead to additional support for this model. Recent theoretical studies, taking into account the effect of a Jahn Teller distortion of the T2 Asi levels have given an insight into the stability and the electronic structure of the defect pair. Further, ODENDOR studies have directly confirmed this model and allowed one to specify the lattice location and the charge state of the Asi ion. The pair structure of this defect implies a reconsideration of the charge states of the EL2 defect, as well as the origin of the optical absorption bands for which transitions on the Asi ion and intracenter bands have also to be considered. The model leads further to a description of the metastable configuration : an arsenic molecule at the gallium vacancy site, the electronic structure of which is calculated. The vacancy related defects, known from electron irradiation studies, are not detected in LEC grown GaAs as native defects.
Metastable Defects in Silicon
Authors: Chantre A.
Published: March 2011

Originally discovered in compound semiconductors, metastability is now being observed for many defects in silicon as well. Simple considerations indeed suggest the existence of alternate, metastable configurations for ab large variety of defect complexes, even as simple as ionic pairs. Techniques to isolate these excited defect configurations are also now well established, and being used routinely in a number of laboratories. This paper will review the recent achievements in this field. Selected examples will be described to illustrate the status of research on metastable defects in silicon.
Effects of Growth Conditions on EL-2 Concentration in OMVPE- GaAs
Authors: Venkatasubramanian R. , Lee W. I. , Ghandhi S. K. , Borrego J. M.
Published: March 2011

We have studied, using DLTS, the EL-2 concentration in unintentionally doped OMVPE n-GaAs as a function of growth conditions such as partial pressure of Arsine, Trimethylgallium and growth temperature. The partial pressure dependencies are used to develop a model for the formation of EL-2 in the OMVPE process. The EL-2 concentration also shows a near inverse dependence on growth temperature.
Properties of the EL2 Level in Organometallic Ga1−xAlxAs
Authors: Cherifa A. Ben , Azoulay R. , Guillot G.
Published: March 2011

We have studied by means of deep level transient spectroscopy and photocapacitance measurements deep electron traps in undoped Ga1−xAlxAs of n-type grown by metalorganic chemical vapor deposition with 0≤x≤ 0.3. A dominant deep electron trap is detected in the series of alloys. Its activation energy is found at EC-0.8 eV in GaAs and it increases with x. Its concentration is found nearly independent of x. For the first time we observed for this level in the Ga1−xAlxAs alloys, the photocapacitance quenching effect typical for the EL2 defect in GaAs thus confirming clearly that EL2 is also created in MOCVD Ga1−xAlxAs.
Absolute Pressure Derivatives of Deep Level Defects in III-V Semiconductors
Authors: Nolte D. D. , Walukiewicz W. , Hailer E. E.
Published: March 2011

Based on transition metal reference levels, we present absolute pressure derivatives for band-edges in GaAs and InP and defects in GaAs. The defect deformation potentials are directly related to the electron-lattice coupling which drives lattice relaxation around the defects. We find an exceedingly large inward lattice relaxation of the EL2 defect in GaAs upon electron emission.
Thermal Annealing and Cooling-Rate Dependent Electronic Properties of Bulk GaAs Crystals
Authors: Parsey J. M. , Asom M. T. , Kimerling L. C. , Sauer R. , Thiel. F. A.
Published: March 2011

Changes in the electronic properties of bulk GaAs crystals, grown from melts of varied As:Ga ratios, and Si-donor concentrations, were investigated by annealing in the temperature range 850°C to 1050°C. We found a gradual reduction of the free carrier concentration, a corresponding decrease in the luminescence spectral intensity, and a suppression of the near band-edge peaks with annealing time at any temperature. Deep level and impurity concentrations remained essentially constant. The magnitude of these changes was found to be determined predominantly by the annealing time and temperature, and the starting composition of the material We argue for a non-radiative native acceptor defect, or defect complex, forming during the annealing cycle. We present here the thermodynamic interpretation for this behavioi in terms of point defect equilibria.
Time Resolved Photoluminescence of Yb in InP
Authors: Klein P. B.
Published: March 2011

Time resolved photoluminescence (PL) measurements of the internal 4f-4f transitions of Yb3+ have been carried out in InP and GaP. In InP a nonexponential component is observed in the PL decay, and is interpreted in terms of carrier capture by nonequilibrium Yb3+. At low temperatures the exponential component is found to be much faster (≈12.5 μsec) than expected, and is tentatively associated with a weak coupling to resonant valence band states. As the temperature is increased, the PL intensity and the exponential component of the excited state lifetime are quenched with a thermal activation energy of ≈0.1 eV. This is interpreted as being due to the emission of a hole into the valence band by the neutral Yb acceptor.
Observation of the Ga Self-Interstitial Defect in GaP
Authors: Lee K. M.
Published: March 2011

The first experimental evidence of an isolated self-interstitial defect in an as-grown semiconductor is reported. An optically detected magnetic resonance spectrum observed in GaP [0] was identified as arising from a Ga selfinterstitial. The large isotropic hyperfine splittings (g = 2.003 (3), A(69Ga) = 741(5)×10−4 cm−1 and A(71Ga) -941[5]×10− 4 cm−1) revealed that a single Ga atom at a Td-symmetric site is the center of the defect. The interstitial nature is established by theoretical considerations. The spin dependent recombination process is attributed to a non-radiative donor-acceptor-pair process involving the Ga++ state which is in competition with a radiative (Odeg; - A° ) pair process and an electron capture process at O-donor.
Optically Detected Magnetic Resonance Studies of Complex Antisite-Related Defects in Bulk Lec GaP
Authors: Chen W. M. , Godlewski M. , Monemar B. , Gislason H. P.
Published: March 2011

A range of PGa antisite-related complex defects in LEC GaP:Cu, Li was observed with optically detected magnetic resonance. These isoelectronic defects are formed by a compensation of the PGa double donor by the CUGadouble acceptor on adjacent cation sites. T electronic structure of these defects is discussed, as well as their role in non-radiative recombination.
Ge Related Defect-Complex Induced Luminescence in InGaAsP
Authors: Arora B. M. , Chakravarty S. , Chandvankar S. S. , Rajalakshmi R. , Srivastava A. K.
Published: March 2011

Germanium doping of InGaAsP epitaxial layers grown by liquid phase epitaxy produces n type conduction with a net distribution coefficient KGe∼ 5×10-3. In addition, Ge doping introduces a broad band (∼0.2eV) of efficient luminescence which is red shifted with respect to the band edge. The intensity of this band grows with increasing Ge concentration. In all the samples, the integrated intensity of the broad band varies relatively less in the temperature range 15K to about 90K. At higher temperatures, the intensity falls exponentially with an activation energy of 0.05 - 0.07 eV. The emission spectra are compared with the configuration-coordinate model of the emission from a Ge related complex.
A Comparative Study of Different Rapid Annealing Techniques on Electrically Active Defects in Unimplanted Gallium Arsenide
Authors: Marrakchi G. , Guillot G. , Nouailhat A.
Published: March 2011

The present paper describes the evolution of native defects and the introduction of new defects by transient annealing on unimplanted Bridgman (B) or Liquid Phase Epitaxy (LPE) Gallium Arsenide (GaAs). Three techniques covering all the timescales below those available with the conventional furnace annealing were used: Pulsed Electron Beam Annealing (PEBA), Continuous Wave Laser (CWLA) and Rapid Thermal Annealing (RTA). Electronic defects have been investigated by Deep Level Transient Spectroscopy (DLTS). The evolution of native defects and the introduction of new defects, are strongly dependent on the annealing technique. A significant decrease of EL2 concentration has been observed after PEBA, but it is not affected by CWLA or RTA under our annealing conditions. On the contrary, the other native defects EL6 and EL3 are completely annealed by RTA and PEBA. Furthermore, both DLTS spectra recorded after PEBA and RTA on the B substrates show introduction of new defects. However, CWLA does not affect the defects present in B GaAs, but an electron trap termed PL1 was introduced by this treatment in a thin oxide layer formed on the LPE grown GaAs.
Extended X-Ray Absorption Fine Structure Studies of Impurities in Semiconductors
Authors: Sette F. , Pearton S. J. , Poate J. M. , Rowe J. E.
Published: March 2011

We discuss Extended X-ray Absorption Fine Structure (EXAFS) experiments on impurities in semiconductors. The local structure of the impurity site is determined for the first, second and third neighbor shells. These studies are carried out on absorption edges in the soft x-ray region using a novel fluorescence detection scheme which reveals improved detection sensitivity when compared with more standard electron Auger yield methods. The higher detection sensitivity allows structural studies at atomic densities as low as 1018 at/cm3 and this technique is used to study the local structure of P and S impurities in GaAs and of S in Alx Gal−x, As at concentrations of 1019–1020 at/cm3. The P atoms are substitutional on As sites, and a breathing relaxation of the P first shell Ga atoms is responsible for a P-Ga distance of 2.38Å, which is 0.07Å shorter than the As-Ga distance in GaAs(2.45Å). No detectable relaxation is observed in the P second and third atomic shells. In S-doped GaAs we find two different populations of S-Ga bonds with nearly equal intensity and both with S located on the As sub-lattice. These findings indicate two different configurations of substitutional S in GaAs. The coexistence of two similarly populated, charge compensating configurations is the first structural evidence which allows us to explain the observation that in n-doped GaAs the electrical activity of donors is lower than the atomic concentration. Finally, we present experimental results on S impurities in AlxGal−x, As (0.2<x<0.5). In this system, at the Al concentrations we studied, the S impurities are bound only to Al and not to Ga atoms. We report the formation of an extended complex which is discussed in connection with the structural identification of DX centers in these materials.
Excitation Spectroscopy of the Defect Bound Excitons in MBE GaAs
Authors: Charbonneau S. , Mcmullan W. G. , Henry M. O. , Thewalt M. L. W.
Published: March 2011

The origin of the complex photoluminescence line series often observed in MBE-grown GaAs has been the subject of considerable recent study. We report on the results of high resolution, high sensitivity resonant excitation measurements which conclusively prove the lines to result from the recombination of excitons bound to a series of acceptors. New details of the properties of the bound excitons and acceptors are revealed. The direct connection between this acceptor series and an often-observed series of broader, lower energy lines is also established. Some preliminary studies of this line series under applied magnetic fields are also described.
Optically Detected Magnetic Resonance of Donors in AlxGa1−x as with High AlAs Fraction
Authors: Kennedy T. A. , Magno R. , Glaser E. , Spencer M. G.
Published: March 2011

Optical and magnetic properties of donors in high AlAs-fraction AlxGa1−x As have been determined using optically-detected magnetic resonance. Many samples exhibit a sharp resonance at g = 1.95 detected on midgap luminescence. One high-quality sample exhibits an exhange-broadened line which reveals a distribution in donor-acceptor pair separations on moderately deep emission. A second high-quality sample exhibits the donor ODMR on donor-to-shallow- acceptor photoluminescence.
Lattice Relaxation of the DX Centers in Ga1−x Alx As and of the Pressure–Induced Deep Donors in GaAs
Authors: Li M. F. , Shan W. , Yu P. Y. , Ransen W. L. , Weber E. R. , Bauser E.
Published: March 2011

Deep Level Transient Spectroscopies (DLTS) and capacitance transient techniques have been applied to GaAs:Si and to Ga1−xAlxAs:Te (x=0.35) under quasi-hydrostatic pressure using a diamond anvil cell. By substituting the experimental pressure coefficients of the defect energies into a model proposed by Li and Yu (Solid State Commun. 61, 13 (1987)) we concluded that both the DX center in the GaAlAs alloy and the pressure-induced deep donor (PIDD) in GaAs have large lattice relaxations associated with them.
Tem Investigation of Strain Relaxation in ZnSe/ZnSxSe1−x Superlattices Grown by MBE
Authors: Petruzzello J. , Boser O. , Kellawon P.
Published: March 2011

The relaxation mechanisms of ZnSe/ZnSxSe1−x superlattices grown by molecular beam epitaxy was studied by transmission rAeclmn icroscopy. The relaxation of misfit strain occured in part by conventional misfit dislocations that reside in the superlattice-buffer layer interface and in part by dislocations pinned at individual layer interfaces of the superlattice. The generation of misfit dislocations at the superlattice-buffer layer interface is inhibited by the misfit strain between individual superlattice layers. Therefore a significant amount of overall strain is present even after 1 μm of growth. Because misfit dislocations are not sufficient in relief of the misfit strain cracks are able to propagate
A Molecular Rebonding Bistable Defect in Silicon: the Interstitial Carbon-Substitutional Carbon Pair
Authors: Song L. W. , Zhan X. D. , Benson B. W. , Watkins G. D.
Published: March 2011

A new type of bistable center is observed in electron-irradiated Si and identified as an interstitial carbon-substitutional carbon pair by combining several spectroscopic techniques. In the positive and negative charge states, the stable configuration of the defect involves a carbon-silicon interstitialcy (each atom 3-fold coordinated) next to a 4-fold coordinated substitutional C atom. In the neutral state, the defect rearranges its bonds so that both C atoms are substitutional (4-fold coordinated) with a 2- fold coordinated Si atom nestled between. Configurational coordinate energy surfaces are determined for each of the three charge states.
The Diffusivity of Self-Interstitials in Silicon
Authors: Morehead Frederick F.
Published: March 2011

Values of the diffusivity of silicon self-interstitials have been previously inferred from analyses of the in-diffusion of Au in undislocated Si, e.g., 2×10-7 cm2 s-1 at 1100 °C. A more complete analysis by numerical integration of the effective diffusion equation with fewer assumptions yields ahigher minimum value, 6×10-6 cm2s-1 at 1100 °C. Recently published experiments showing no measurable difference in the oxidation-reduced diffusion of Sb in Si at 10 and 40 microns are consistent with this high value.
The Structure of the (001)Si/SiO2 Interface
Authors: Ourmazd A. , Bevk J.
Published: March 2011

We show that a careful examination of previous microscopic structural data from the Si/SiO2 interface reveals that the presence of an epitaxial interfacial oxide cannot be ruled out, and describe the conditions necessary for a definitive search for an intervening layer between c-Si and a-SiO2 We present electron diffraction and lattice imaging data, which establish the c-Si→a-SiO2 transition to take place via a crystalline layer ˜7 A thick. Modelling of lattice images in two projections indicates the crystalline oxide to be tridymite, a stable, bulk phase of SiO2
Defect Microchemistry at the SiO2/Si Interface
Authors: Rubloff Gary W.
Published: March 2011

A dominant, intrinsic chemical reaction path in SiO2/Si systems is the decomposition reaction Si +SiO2 → 2 SiO. Controlled analytical studies have elucidated the microchemical and microstructural aspects of this process and revealed that nucleation of the reaction occurs at existing defect sites. At an earlier stage of reaction, the same decomposition chemistry leads to electricl activation of the defects, as seen in breakdown and hole trapping phenomena. By careful and systematic control of ambient conditions during annealing, it is shown that the evolution of electrically active defects follows the same decomposition chemistry as does the physical deterioration of an entire oxide layer. These aspects of defect chemical behavior suggest implications for both defect identification and defect control in thin SiO2 layers on Si.
Electrical, Optical and Structural Properties of Thin SiO2 Films On Si
Authors: Ravindra N. M. , Russo O. L. , Fathy D. , Narayan J. , Heyd A. R. , Vedam K.
Published: March 2011

Breakdown voltage, static current-voltage, spectroscopic ellipsometry (SE), electrolyte electroreflectance (EER) and high resolution transmission electron microscopic (HRTEM) studies of thermally grown thin films of SiO2 on silicon (800°C - dry) are reported here. The investigation of the electrical properties of these films lead us to suggest the criteria for determining the breakdown voltage of these 20nm thick SiO2 films. The Fowler-Nordheim tunneling contribution to current conduction mechanisms in SiO2 has been considered in evaluating these criteria. SE, EER & HRTEM studies have been performed on SiO2 films of thicknesses in the range of 1–20 nm. These studies lead us to determine the thickness of the non-stoichiometric silicon-rich oxide existing at the Si-SiO2 interface. EER studies show that the relative surface state densities for different film thicknesses can be determined. The role of the transition region in determining the dielectric strength of thin SiO2 films is discussed.
Measurement of Optical Absorption in Very Thin Low-Loss SiO2 Films
Authors: Curran Robert M. , Crook Thomas M. , Zook J. David
Published: March 2011

While low levels of optical absorption are easily measured in SiO2 bulk samples or optical fibers, we present here a method of detirmining low levels of absorption in thin films of SiO2. Films are deposited on top of high reflectivity multi-layer miriors, and absorption is derived from the time decay in a resonant cavity of threj mirrorsgt 633 nm. Absorption coefficients on the order of 1 cm−1. (k = 10−5) can be measured in films as thin as 100 Angstroms.

With this method, we find that absorption at 633 nm can be induced in SiO2 films by exposing them to a He-Ne plasma discharge. Although the plasma radiation (>10 eV) is absorbed near the SiO2 surface, the plasma-induced absorption is uniform within the SiO2 film. This was shown by plasma irradiation of SiO2 films of 4arying thickness, together with computer calgulation of the optical properties of multilayer thin films. Similar absorption behavior has been reported in SiO2 optical fibers and may be due here to DIA (Drawing-Induced Aisorption) centers or NBOHCs (Non-Bridging Oxygen Hole Centers).
Enhanced Conduction In Sipos Films With High Oxygen Content
Authors: Chang K.-T. , Lam C. , Rose K.
Published: March 2011

Polysilicon films with high oxygen content (SIPOS) have been prepared by LPCVD. These films have a two-phase structure with silicon crystallites surrounded by amorphous oxide, as confirmed by TEM and HRTEM measurements. Increasing the ratio of nitrous oxide to silane, R, during growth allows us to vary the oxygen concentration. Contrary to expectation, we observe a region where conduction increases as R is increased from 1 to 10. This can be accounted for by deviations from monotonicity in the dependence of silicon volume fraction on R. We also observe some influence of the SIPOS/silicon interface on conduction.
The Effect of Ge Segregation on Oxidation of Si
Authors: Frey E. C. , Parikh N. R. , Swanson M. L. , Numan M. Z. , Chu W. K.
Published: March 2011

We have studied oxidation of various Si samples including: Ge implanted Si, CVD and MBE grown Si(0.4–4% Ge) alloys, and MBE grown Si-Si(Ge) superlattices. The samples were oxidized in pyrogenic steam (800–1000°C, atmospheric pressure) and at low temperature and high pressure (740°C, 205 atm of dry O2). The oxidized samples were analyzed with RBS/channeling and ellipsometry.

An enhanced oxidation rate was seen for all Ge doped samples, compared with rates for pure Si. The magnitude of the enhancement increased with decreasing oxidation temperature. For steam oxidations the Ge was segregated from the oxide and formed an epitaxial layer at the Si-SiO2 interface; the quality of the epitaxy was highest for the highest oxidation temperatures. For high pressure oxidation the Ge was trapped in the oxide and the greatest enhancement in oxidation rate (>100%) was observed.
Physical and Chemical Properties of Silicon Dioxide Film Deposited by New Process
Authors: Goda Takuji , Nagayama Hirotsugu , Hishinuma Akihiro , Kawahara Hideo
Published: March 2011

A new coating process of silicon dioxide (SiO2) “LPD” process, has been developed recently. Silicon dioxide (SiO2) film can be deposited on any substrate at the room temperature by immersing in hexafluorosilicic acid (H2SiF6).

In this study, physical and chemical properties of the “LPD- SiO2” film were investigated by using XPS, IR, ellipsometry, and etch rate measurement. The properties of this film deposited at the room temperature were almost the same as those of plasma CVD. The “LPD-SiO2” film without annealing was contained traces of F and OH. However, by annealing, F and OH were rapidly evaporated from the film and the film was getting densified.

As the “LPD-SiO2” film deposited at the room temperature showed very good results of chemical etching rate and of step coverage, it is expected that it is possible to use this “LPD- SiO2” film in the wide range of industrial area.
Film Growth Mechanism of Photo-Chemical Vapor Deposition
Authors: Inushima T. , Hirose N. , Urata K. , Ito K. , Yamazaki S.
Published: March 2011

The photo-chemical vapor deposition (CVD) of SiO2 and SiN2 were investigated using 185 nm light of a low pressure mercury lamp. The film thickness deposited on the substrate was the function of the distance from the substrate to the light source and its relation was investigated by changing the reaction pressure. From these investigations, the space migration length of the active species was estimated, which was, at the processing pressure of 400 Pa, about 10–20 mm. This migration length was confirmed by a model calculation. The step coverage of the film was investigated by the use of a two-dimensional capillary cavity. It was shown that the thickness decayed exponentially with the depth in the cavity. The decay constant did not show temperature dependence. From this result, the surface migration of the active species produced by photo-CVD was reported. To confirm this migration we presented a substrate- size effect of photo-CVD, which became obvious when the substrate size became smaller than the space migration length of the active species. From these results, the film growth mechanism of photo-CVD was discussed.
Study of SiO2 Formation by Plasma Treatment of SiO Thin Films
Authors: Perriere J. , Pelloie B. , Rochet F. , Fogarassy E. , Slaoui A. , Dufour G. , Roulet H. , Fromnt M.
Published: March 2011

Our Present Understanding of the Mechanisms of the transformation of SiO films under treatments in O2 or Ar plasma at room T, is presented. RBS, IR absorption, XPS, RHEED and TEM techniques have been used to investigate the composition, the chemical and structural nature of the films after oxidizing or non oxidizing treatments. In O2 plasma, SiO is converted into Si02 by room T plasma anodization. The initial step of SiO oxidation, which is believed to be the transformation 2SiO→Si+SiO2, was studied in Ar plasma. We show that the as deposited SiO (not a mixture of Si and SiO2) is subject to disproportionate into the later compounds and that the effects of irradiation by low energy electrons at room T (plasma treatment) are similar to those observed for high T treatments (rapid thermal annealing).
Effects of Si Implantation on Sb Diffusion In Sb-Silica Spin-On Layers
Authors: Moriya N. , Kalish R. , Brener P. , Richter V.
Published: March 2011

The effects of Si implantation (2×1015 · cm-2) on the diffusion of Sb in Sb doped silica (SiO2) spin-on layers and on their hardness were studied. RBS analysis and AES depth profiling showed that the implantation greatly retarded the Sb diffusion (1000–1200°C, 10 sec) in the oxide layer. Hence the high level of Sb near the SiO2/Si interface, which is clearly seen for the unimplanted part of the sample was not noticible in the non implanted part. AES depth profile measurements also showed that the deposited oxide layers were more sputter resistant as a result of the implantation. The above observations are related to the ion induced radiation damage.
Degradation of TiSi2/n+-Polysilicon Interfaces Due to High Temperature Processing
Authors: Shenai K. , Piacente P. A. , Smith G. A. , Lewis N. , Mcconnell M. D. , Norton J. F. , Hall E. L. , Baliga B. J.
Published: March 2011

Analytical results obtained from detailed Secondary Ion Mass Spectrometry (SIMS), Rutherford Backscattering Spectrometry (RBS), Auger analysis, Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM) of ∼ 2000Å TiSi2/n+ polysilicon interfaces are reported for thermally annealed silicide samples and silicide samples subjected to further high temperature processing. The LPCVD polysilicon was heavily POCI3 doped at 900°C and TiSi was formed by rf sputtering 1000Å Ti and forming the silicide using ?wo successive thermal anneals at 600°C and 800°C in forming gas resulting in a silicide sheet resistance R of 1.45 Ω/□. The high temperature process stability of the silicide – polysilicon interface was investigated by systematically stressing the polycide at process temperatures in the range of 700° C to 1100° C. The silicide was stable for temperatures up to 900° C; however, significant degradation in the silicide sheet resistance, phosphorus, silicon, and titanium redistribution, and agglomeration and film breakage of TiSi2 were observed at higher process temperatures.
Formation of PtSi Using Polycrystalline Si and Different Annealing Sequences
Authors: Chang Chin-An , Segmüller Armin
Published: March 2011

Formation of PtSi on As-doped polycrystalline Si is studied using different annealing sequences. An incomplete reaction between the Pt and Si is observed using a one-temperature anneal at 550 ° C, with unreacted Pt remaining in the film which is undesirable for the device processing. Using a three-temperature annealing sequence at 200–300–550 ° C in a N2-H2 mixture, a complete reaction is observed between Pt and Si, with no unreacted Pt detected. The results are similar to that using single crystal Si, except for the less-oriented PtSi formed. The three-temperature annealing process described has thus been shown useful to the fabrication of PtSi contacts at device areas containing either single crystalline or polycrystalline Si.
Piezoresistive Properties of Boron-Doped PECVD Microcrystalline Silicon Films
Authors: Guo Shu Wen , Tan Song Sheng , Wang Wei Yuan
Published: March 2011

The piezoresistive properties of boron-doped PECVD microcrystalline Si films (μc-Si) deposited on SiO2 coated Si, covar or quartz substrates have been investigated. The relations between the gauge factor (G.F.) and doping concentrations as well as the film thickness etc. have been obtained experimentally. The maximum longitudinal G.F. of 25 and 20 are measured for Si and covar substrates respectively. An expression for calculating G.F. of P-type μc-Si is derived theoretically by use of the splitting model of heavy and light hole band at k=0 and the thermionic emission theory. The calculated dependences of G.F. on the doping concentrations, grain size and trap state density agree well with the experimental results, which offer a better understanding of the piezoresistive characteristics of μc-Si or poly-Si, and enable optimized design and fabrication of μc-Si or poly-Si strain gauges.
Polysilicon Super Thin Film Transistor Technology
Authors: Noguchi Takashi , Hayashi Hisao , Ohshima Takefumi
Published: March 2011

Advanced super thin(of less than 800Å) polysilicon films with the grain size of more than lum were developed by applying the Si+implanted amorphization and subsequent annealing. With this film, TFT with superior characteristics could have been fabricated on quartz or SiO2/c-Si substrate. At the process of 600°C, field effect electron mobility as large as 60cm 2/V.s. was obtained. Furthermore, using the high temperature process of 1000°C, electron and hole mobility increased to the value of 120 and 80cm2/V.s, respectively. The values of field effect electron mobility were almost constant over a wide temperature range. The CMOS scanner was fabricated and operated faster than 5MHz. These advanced polysilicon TFT's have a great impact on large size LSI.
Effects of Silicon Implantation and Processing Temperature on Performance of Polycrystalline Silicon Thin-Film Transistors Fabricated from Low Pressure Chemical Vapor Deposited Amorphous Silicon
Authors: Chiang Anne , Huang Tiao Y. , Wu I-Wei , Zarzycki Mark H. , Fuse Mario
Published: March 2011

Silicon implantation has been found to dramatically enhance the grain size of polysilicon crystallized from LPCVD a-Si by retarding the nucleation process at the substrate interface. Corresponding improvement in TFT device performance was also observed, resulting in field effect mobilities as high as 109 cm2/Vs in devices with 1000 Å thick Si active layer. This effect is more significant in device fabrication processes with higher temperature, possibly due to increasingly efficient removal of implant related defects.
Leakage and Transconductance in Polysilicon Thin Film Transistors: Effect of Grain Boundary Hydrogenation
Authors: Qian Feng , Kim Dae M. , Kawamoto Galen H.
Published: March 2011

The n- and p-channel field effect transistors are fabricated in as-deposited and grain boundary passivated polysilicon thin films. The performance of these thin film transistors (TFT's) is characterized and compared. Specifically, the transconductance and leakage behavior are discussed in detail in correlation with the grain boundary properties. The I-V characteristics are modeled from a unified point of view.
Poly-Silicon Deposition by Evaporation for TFTs
Authors: Schmolla W. , Diefenbach J. , Blang G. , Senske W.
Published: March 2011

Poly-Si films were e-gun evaporated onto glass substrates. The Hall-mobility for holes was found to be about 2 cm2/Vs in undoped poly-Si films deposited at 400°C and 9 cm2/Vs at 500°C. TFTs were fabricated on the base of poly-Si evaporation technique on borosilicate glass at a highest process temperature of 550°C without ion implantation. The electrical TFT characteristics yield electron field-effect mobilities higher than 10 cm2/Vs as well as threshold voltages less than IV and an on/off current ratio in excess of 104.
Crystallization of Amorphous LPCVD Silicon Films and Application to Bipolar and Thin Film Transistors
Authors: Hatalis Miltiadis K. , Greve David W.
Published: March 2011

We studied the crystallization of LPCVD amorphous silicon films by TEM and found that the grain size of crystallized films depends upon the deposition and annealing conditions. The grain size increases as the deposition and/or the annealing temperature decreases. We also investigated the application of crystallized films in the fabrication of polysilicon emitter bipolar transistors and thin film transistors. The performance of bipolar transistors was found to have a small dependence on the grain size. In contrast, the performance of thin film transistors was strongly dependent upon the grain size.
On the Temperature Dependence of Resistivity of Polycrystalline Silicon Films
Authors: Rodder Mark S. , Antoniadis Dimitri A.
Published: March 2011

It is shown that the grain boundary (GB) in polycrystalline-silicon (poly-Si) films need not be modeled as a temperature-dependent potential barrier or as an amorphous region to explain the temperature (T) dependence of resistivity (ρ) in p-type poly-Si films at low T. Specifically, we consider that QB defect states allow for the tunneling component of current to occur by a two-step process. Incorporation of the two-step process in a numerical calculation of ρ vs. T results in excellent agreement with available data from 100 K to 300 K.
Influence of the Decoration by Dislocations on Grain Boundary Passivation by Hydrogen in Silicon
Authors: Ammor L. , Mathian G. , Martinuzzi S.
Published: March 2011

In large grained polycrystalline silicon, the recombination activity of G.B.'s and their passivation by hydrogen is found to be dependent on the decoration by dislocations. Dislocations appear to be preferential paths for in-diffusion, at a depth of a few hundreds of pim's. Similar enhancements of diffusion and passivation exist in grains around dislocations.
Hacroscopic Defects in Epitaxial Silicon on Simox and in Annealed SIMOX
Authors: Mogro-Campero A. , Lewis N. , Al-Marayati S.A.
Published: March 2011

Epitaxial silicon layers of 5¼m were grown on SIMOX wafers. The dislocation density decreases by more than an order of magnitude as a function of distance away from the buried oxide. Shallow pits (about 0.5 urn deep and several um wide) are observed on the epitaxial layer with a density of 1-2 mm2. Their density did not change with various processing variations. A search for the origin of the pits by transmission electron microscopy reveals that they may be associated with regions of irregularly thin and sometimes missing buried oxide, which appear after the usual high temperature SIMOX annealing step. These defective regions in the buried oxide appear to initiate twinned growth in the epitaxial silicon, and are associated with pits at the top epitaxial silicon surface.
Oxygen Ion Implantation into Germanium
Authors: Sjoreen T.P. , Ravindra N.M. , El-Ghor M.K. , Fathy D.
Published: March 2011

Single crystal (111) and (100) Ge wafers were implanted with 16O (180 keV, 2.0 x 1018/cm2, 14–28 ¼A/cm2 ) at substrate temperatures of 250, 330, and 500°C. Implanted samples were annealed at 350, 450, 550, and 650°C for 30–90 minutes in an Ar ambient. Rutherford backscattering channeling analysis and cross-sectional transmission electron microscopy indicate that an amorphous buried layer is formed by implantation and that the overlayer contains a dense network of precipitates. Electron spin resonance measurements indicate that the layer does not contain GeO2, but rather oxygen deficient GeO2. Annealing of samples up to 550°C showed no change in the morphology, however, after annealing at 650°C the buried layer was gone and all that remained was a damaged Ge substrate with little or no oxygen. Further annealing for 60 min left nearly virgin Ge.
Evidence for Oxygen Concentration Changes Induced by Low-Temperature 0–18 Implantation into a SIMOX Buried-Oxide Layer
Authors: Scanlon P.J. , Hemment P.L.F. , Robinson A.K. , Reeson K.J. , Chater R.J. , Kilner J.A. , Harbeke G.
Published: March 2011

RBS, SIMS, and IR measurements have been made on a SIMOX wafer, implanted with a second, low-temperature oxygen implant. These measurements indicate changes in the oxygen/silicon ratio in the buried oxide layer and differences in the annealing behaviour of the original layer and the double implant layer.
Soi Formation by a Line-Source Electron Beam and Electrical Characteristics
Authors: Hada H. , Okabayashi H. , Saito S. , Nakamura T. , Kawase Y.
Published: March 2011

Crystal quality of SOI and electrical characteristics of p-MOSFETs fabricated in SOI films have been studied. The SOI recrystallization is done by a cw-operated, high-power, line-source and line-shaped electron beam annealing. Single crystal SOI strips, 15~20¼mxa few mm in sized, are formed with a good uniformity on a 4 inch diameter wafer by adopting the step and repeat system in the annealing apparatus. p-MOSFETs with ~90% field effect mobility of the bulk values are fabricated in the SOI films. The electrical characteristics of p-MOSFETs, fabricated in the SOI regions beyond the lateral seeding distance (~15¼m), are found to be independent of the low angle grain boundary density in the MOSFET channel, when the low angle grain boundaries extended toward the channel width direction.
SOI Structures Formed Using Line-Source Electron Beam Recrystallization
Authors: Moore Cameron A. , Meyer Jack D. , Fukumoto Jay T. , Szluk Nicholas J. , Thompson Lance R. , Knapp James A. , Collins George J. , Berkman Samuel
Published: March 2011

Recrystallization of silicon-on-insulator (SOI) films using a line-source electron beam is described. This unique heat source can continuously emit several kilowatts of - 5 keV electrons into a beam 150 mm in length and - 2.5 mm in width, an exposure area which allows processing of 100 mm substrates in a single pass. An attractive aspect of this beam is the ability to control the beam profile, which in turn allows one to influence the thermal gradients present during recrystallization. Using a tightly focussed beam to recrystallize the SOI layer results in a film whose physical properties are generally attributed to films grown with a high thermal gradient at the solidifying liquid-solid interface (highly branched subboundaries with a maximum spacing of - 20 microns and several degrees of angular mismatch.) By reducing the gradient at the growth interface it is possible to achieve unbranched sub-boundaries with over 70 micron spacing and less than 0.5 degrees of out-of-plane tilt misalignment.
Large Diameter Soi Wafers by Zone-Melting-Recrystallization
Authors: Zavracky P. M. , Vu D. P. , Allen L. , Henderson W. , Guckel H. , Sniegowski J. J. , Ford T. P. , Fan J. C. C.
Published: March 2011

A pilot production Zone-melting Recrystallization system was designed and built with a capability to handle 25 wafer batches of 4“, 5“and 6“wafers. The design addresses several production requirements including high throughput, batch processing and automation. Measurements on product wafers indicate that material quality was not sacrificed to achieve production throughput levels. Exceptional structural quality and good electrical properties have been obtained on SOI wafers produced within this system. Specifically, defect densities as low as 5 X 104 /cm2 a level an order of magnitude lower than previously reported, have been achieved while the minority carrier lifetime of up to 30 microseconds, intrinsic dopant level < 2 X 1015 /cm3 and junction leakage below 1 X 1016 amperes/cm2 are either as good as or better than previously reported values. We believe that defect free ZMR material will become a reality.