bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of Transmission Electron Microscopy to Solving Defect Issues in III-V Alloy Semiconductors and Devices
Authors: Ueda O. 
Published: September 2012

ABSTRACTIn this paper we provide a review of materials issues in the III-V alloy semiconductor system and examine the role of such issues in the degradation of semiconductor lasers and LEDs.Among the major materials issues are the formation of defects and thermal instability of the crystals; we will discuss both of these processes, giving relevant examples. It is convenient to divide crystal defects into two classes: interface defects are bulk defects. Among the former type of defects are stacking faults, V-shaped dislocations, dislocation clusters, microtwins, inclusions and misfit dislocations. Defects belonging to the second class include precipitates and dislocation loops. Thermal instability in crystals during growth also leads to structural imperfections which can affect device properties. One example is the formation of quasi-periodic modulated structures due to spi nodal decomposition of the crystal either at the liquid/solid interface or the growth surface. Another is the formation of ordered structure which also occurs on the growth surface through migration and reconstruction of deposited atoms.We discuss optical device degradation in terms of three major degradation modes: rapid degradation, gradual degradation and catastrophic failure. In devices which degrade by rapid degradation, it is found that recombination-enhanced dislocation glide and climb are responsible. We examine the ease with which these phenomena occur in various hetero-structures and attempt to determine what the dominant parameters are. Gradual degradation takes place presumably due to recombination-enhanced point defect reaction in GaAlAs/GaAs-based optical devices. This degradation mode can be enhanced by the presence of stress due to lattice mismatch in the system. However, in InGaAsPAEnP-based devices, gradual degradation is not observed. In GaAlAs/GaAs DH lasers, catastrophic failure is found to be the result of catastrophic optical damage at a mirror or defect. Again, however, InGaAsP/InP DH lasers do not suffer from this form of degradation. In each degradation mechanism, the role of defects in the degradation and methods of elimination of degradation are discussed.
Rapid Structural Defect Mapping of Bulk II-VI Semiconductors Using White-Beam Synchrotron Topography and X-ray Rocking Curve Analysis
Authors: Marzio Don Di , Casagrande Louis G. , Lee Myung B. , Fanning Thomas , Dudley Michael 
Published: September 2012

ABSTRACTNondestructive characterization techniques for substrates, epilayers, and device structures are becoming increasingly important in the semiconductor industry. Synchrotron-based white-beam x-ray topography, x-ray rocking curve measurements, and etch pit density were used to map the defect structure in a variety of CdTe and CdZnTe single crystal substrates, which are important for IR detector applications involving HgCdTe. Defects such as low angle grain boundaries have been successfully correlated using topography, rocking curves, and etch pit density, and twins have been observed using topography and rocking curves. The effectiveness of white-beam synchrotron topography for rapid and nondestructive defect analysis and substrate screening is discussed.
Relaxation Defect Characterization of RTCVD Si1-xGex/Si Heterostructjres by Electrical and Optical Techniques
Authors: Souifi A. , Bremond G. , Benyattou T. , Guillot G. , Dutartre D. 
Published: September 2012

ABSTRACTPhotoluminescence (PL) and deep level transient spectroscopy (DLTS) measurements have been carried out on Si1-xGex/Si heterostructures and Si/Si1-xGex/Si double heterostructures with fully strained or partially relaxed layers (0%<xGe<20%) grown by chemical vapor deposition using rapid thermal processing (RTCVD). This study reports strong PL and DLTS results connected to the establishment of relaxation defects in the SiGe layer and at the heterointerface which appear when the layer starts to relax. Strong broad PL bands (defect related) and sharp lines (similar to dislocation related D-lines on Si) have been detected and connected to this relaxation process. These PL results are strengthened by the clear observation, using DLTS experiments on relaxed layers, of interface traps with a maximum energy around Ev + 0.5eV resulting from the presence of misfit dislocations at the SiGe/Si hetero-interface and a deep level at Ev + 0.38eV related to dislocations or relaxation defects in the SiGe layer. Moreover, low temperature PL excitonic transition reported on Si/Si1-xGex/Si double heterostructures is described as a good tool to investigate the relaxation process which occurs in these heteroepitaxial layers.
Monoenergetic Positron Beam Studies of Oxygen in Single Crystal Silicon - Stress Induced Clustering of Oxygen Atoms in Silicon
Authors: Nagai R. , Takeda E. , Tabuki Y. , Wei L. , Tanigawa S. 
Published: September 2012

ABSTRACTA monoenergetic positron beam has been used to investigate the state of interstitial oxygen in Czochralski (CZ)-grown Si with either thermally grown S1O2 (100 nm thick) or silicon oxide (p-SiOx) deposited by plasma enhanced chemical vaper deposition technique on the surface. Both the growth of thermal SiO2 and the deposition of SiOx film resulted in a reduction of the doppler-broadening line shape parameter (S-parameter) for the positron annihilation in the bulk silicon region. Annealing at 450δC, the removal of oxide overlayer or long-term aging at room temperature caused the S-parameter to return to its intrinsic value. It was thought that tensile stress in silicon, induced by the thermal oxidation or the deposition of SiOx films which had compressive internal stress themselves, enhanced the rearrangement of oxygen atoms and caused the formation of oxygen clusters in silicon crystal. Oxygen interstitial clusters can trap positrons leading to the lower S-parameter value for annihilation in the bulk silicon region, because of large overlap with core electrons. The above results suggest that oxygen atoms can absorb lattice strain by clustering and thus prevent the generation of dislocations against external stress in the Si lattice. This results yield an additional explanation of the high mechanical strength of CZ Si crystal.
Optical Study of the Fe3+-Related Emission at 0.5 eV in InP:Fe
Authors: Pressel Klaus , Bohnert G. , Dörnen A. , Thonke K. 
Published: September 2012

ABSTRACTThe 0.5 eV (2.5 μm 4000 cm1) emission band in InP has been studied by optical spectroscopy. By the use of Fourier-transform-infrared photoluminescence we have been able to observe at least a three-fold fine structure in the zero-phonon transitions at ∼ 4300 cm−1 which are studied at different temperatures. Based on the fine structure and the long decay time of 1.1 ms we ascribe the 0.5 eV emission to the 4T1 → 6A1 spin-flip transition of Fe3+. The excitation spectrum of this Fe3+-related emission shows a characteristic fine structure at ∼ 1.13 eV which belongs to a charge-transfer process of the type: Fe3+ + hv (1.13 eV) → [Fe2+, bound hole]. We discuss the excitation mechanism of the 0.5 eV emission by charge-transfer states and compare the results with an emission at 3057 cm1 in GaAs, which we attribute to the same Fe3+ transition (decay time: 1.9 ms).
The Interfacial Reactions in Ti/Si and Ni/Si Systems Observed by a Monoenergetic Positron Beam
Authors: Tanigawa S. , Wei L. , Tabuki Y. 
Published: September 2012

ABSTRACTThe formation of suicides via the thin-film deposition of transition metals onto Si substrates has been investigated by a monoenergetic positron beam. The Doppler broadened spectra of annihilation radiations in the as-deposited state and the silicide-formed state of the Ti/Si and Ni/Si systems were measured as a function of the incident positron energy between 0.1 keV and 30 keV. From the depth dependence of positron annihilation characters, the diffusion length of positron was determined on the basis of one dimensional diffusion models. In the case of the Ti/Si, the formation of the suicides did not induce the shortening of positron diffusion length in Si substrate. On the contrary, the diffusion length of positrons in formed suicides was very short indicating the presence of a great number of positron traps in suicides. From this fact, the moving species during the silicidation may be Ti atoms. On the other hand, in the case of Ni/Si, the silicidation induced a very short diffusion length of positrons in the Si substrate. On the contrary, the diffusion length in the formed suicide is long to a comparable extent expected defect-free metals. From this fact, the moving species may be Si atoms. In the present parer, the first report on the microscopic observation of Kirkendall effect in metal/Si systems by means of a monoenergetic positron beam will be given.
Electron Irradiated InP: A Positron Annihilation Study
Authors: Bretagnon T. , Dannefaer S. , Kerr D. 
Published: September 2012

ABSTRACTPositron lifetime measurements show that electron irradiation produces indium vacancy related defects in InP. Divacancies are also found in semi-insulating and lightly doped p and n-type materials. Temperature investigations show a change in the divacancy charge state.
The Study of Si, Se and O-Implanted GaAs by Slow Positrons
Authors: Fujii S. , Shikata S. , Wei L. , Tanigaw S. 
Published: September 2012

ABSTRACTVariable-energy (0–30keV) positron beam studies have been carried out on 200 keV Se-implanted and 70 keV Si-implanted GaAs specimens before and after annealing for electrical activation. From the measurements of Doppler broadened profiles as a function of incident positron energy, it was found that vacancy clusters with high concentration were introduced in the annealed specimen after Se implantation. From the parallel measurement of electrical characteristics, a higher activation efficiency was found for the higher concentration of vacancy clusters. That fact implies that electrons supplied by the activation of Se also convert the charge state of As vacancies from positive to negative. In contrast, no vacancy clusters were introduced in the Si-implanted GaAs. On the other hand, oxygen clustering was found in annealed specimen after O implantation.
The Effect of Hydrogenation on the Electrical Properties of Crystalline Silicon
Authors: Pankove Jacques I. 
Published: September 2012

ABSTRACTHydrogen ties Si dangling bonds at defects as well as near impurities. Defect passivation leads to dramatically lower surface recombination and increased minority carrier lifetime. Dopant neutralization increases the resistivity of the crystal and the mobility of carriers. The neutralization of donors and acceptors is optimum at different temperatures. Deep levels can also be neutralized.
Local Bonding Structure of Hydrogen in Crystalline Silicon: NMR and Tem Studies
Authors: Boyce J. B. , Johnson N. M. , Ready S. E. , Walker J. , Anderson G. B. 
Published: September 2012

ABSTRACTNuclear magnetic resonance (NMR) and transmission electron microscopy have been used to obtain information on the local structure of deuterium in single-crystal silicon, both for deuterated, phosphorous-doped Si that contains platelet-structured defects and for deuterated boron-doped silicon. In both cases, the NMR spectrum consists of two components, a narrow doublet and a central, unsplit line. The doublet arises from D bonded to Si with the Si-D bond along the <111> directions. The central line, which contains more D than does the doublet, is ascribed primarily to molecular D2 that resides in regions of the crystal where translation and tumbling are inhibited and possibly to some D in weak Si-D bonds.
Passivation of Surface and Bulk Defects in InP
Authors: Balasubramanian Sathya , Kumar Vikram , Balasubramanian N. , Premachandran V. 
Published: September 2012

ABSTRACTThe effect of sulfur and hydrogen plasma treatment on the Schottky barrier and photoluminescence (PL) properties of p-InP is reported. Both the treatments increase the barrier height of Au/p-InP diodes and band to band PL. This is explained as being due to a shift in the surface fermi level position towards the P vacancy related pinning level in the top half of the band gap. The H+ treatment passivates the shallow and deep levels as observed from the C-V depth profile and PL respectively.
Hydrogen Passivation and Reactivation of DX Centers in Se-Doped and Si-Doped AlGaAs - - A Comparison
Authors: Roos G. , Johnsons N. M. , Herring C. , Harris J. S. 
Published: September 2012

ABSTRACTThe effect of hydrogenation on DX centers was evaluated for both Si- and Se-doped AlxGa1-xAs (x=0.26 and 0.23). MBE-grown AIGaAs:Si and MOCVD-grown AIGaAs:Se epilayers were hydrogenated with either monatomic hydrogen or deuterium from a remote plasma at 250°C for 1h. The passivation and subsequent reactivation kinetics were studied with C-V and DLTS techniques. Reactivation was investigated in the space-charge layer of Schottky diodes under different bias conditions. While the Group VI and Group IV deep donors respond similarly to passivation, they display significantly different reactivation kinetics, with thermal dissociation energies of 1.5 eV and 1.2 eV for Se-H and Si-H, respectively. These values are close to the energies previously determined for reactivation of the Si and Se shallow donors in both AIGaAs and GaAs. Therefore, they are not significantly dependent on the Al concentration (x < 0.30) even for donors residing on the As sublattice. Our results are consistent with the Chang-Chadi model of DX centers.
Passivating Complexes in Cd Doped G a As and InP: Microscopic Properties and Electrical Effects
Authors: Moriya N. , Deicher M. , Kalish R. , Keller R. , Magerle R. , Pfeiffer W. , Pross P. , Skudlik H. , Wichert Th. , Wolf H. , Collaboration Isolde 
Published: September 2012

ABSTRACTPerturbed Angular Correlation (PAC) and Hall measurements were used to investigate the stability of the passivating Cd-H complex in GaAs after low energy H implantation (150 eV, 1014 cm−2) at 300 K. From the observed Cd-H pair formation and reduction of hole concentration it is deduced that about 10 % of the implanted H atoms form pairs with the Cd atoms. The influence of the dopant depth profile on the apparent stability in zero bias isochronal annealing experiments is reported. After H loading a reduction of carrier mobility is observed, which is stable up to about 400 K. The formation of Cd-H pairs after low energy H implantation into InP was studied by PAC. By measuring the fraction of pairs in an isochronal annealing experiment, the stability of the pairs is deduced yielding a dissociation energy of ED = 1.8 (1) eV.
Comparison of Trapping States at SiO2/Si Interfaces on si(100), (110), and (111) Prepared by Plasma-Assisted Oxidation and Oxide Deposition, and by Exposure to Atomic H Prior to Oxidation and Deposition
Authors: Yasuda T. , Ma Y. , Habermehl S. , Lucovsky G. 
Published: September 2012

ABSTRACTS1O2 layers, ∼ 15 nm thick, were formed on Si (100), (110), and (111) surfaces by a low-temperature, 200–300°C, plasma-assisted oxidation/deposition process sequence. The distribution of the trap density at the S1O2/Si interface, and in the Si band-gap, Dit, was deduced from capacitance-voltage, C-V, measurements. The values of Dit at midgap varied with crystal orientation in a similar way as in thermally grown oxides. In addition, the low-temperature oxides displayed a characteristic and intrinsic dangling bond state, the so-called Pb center, at ∼0.3 eV above the Si valence-band edge. Samples exposed to atomic H prior to the oxidation and deposition steps, showed an increase in Dit due to a roughening of the Si surfaces, which produced additional broad bands of defect states, at ∼0.5 and ∼0.7 eV above the Si valence-band edge.
Evaluation of Microdefects in As-Grown Silicon Crystals
Authors: Takeno H. , Ushio S. , Takenaka T. 
Published: September 2012

ABSTRACTMicrodefects, revealed as ‘flow patterns’ by preferential etching using Secco's etchant, in as-grown silicon crystals have been investigated by means of a transmission electron microscopy and a preferential etching. In as-grown CZ crystals, grown at the pulling speeds of 0.4 or 1.4 mm/min, dislocation loops and clusters were observed with TEM. The dislocation loops in both crystals are interstitial type. From a thermal behavior of flow patterns by heat treatments, we confirmed that the defects revealed as flow patterns in CZ crystals do not have a similar nature of that in D-defect region of FZ crystals.
The Effect of Vacancies Grown into Silicon on Gold Diffusion
Authors: Graupner R. K. , Van Vechten J. A. , Harwood P. , Monson T. K. 
Published: September 2012

ABSTRACTWe propose a generalized model for gold diffusion in silicon based on the effect of the high concentrations of vacancies and vacancy complexes in the as-grown silicon. The monovacancy profiles calculated using this model are identical to the substitutional gold profiles calculated using the kick-out model. We deposited Au on commercial float zone Si in a vacuum system after the Si had reached the diffusion temperature (1233 K) and had been annealed in various ways. Contrary to previously published reports, we find the electrically active Au with a nearly one-sided profile when the Au is deposited on samples which were preannealed in vacuum. We conclude that annealed silicon surfaces lack the imperfections needed to make them effective sources or sinks for vacancies or self-interstitials. We propose that this can cause a high degree of supersaturation in the as-grown silicon crystal since the point defects cannot annihilate at the surfaces to maintain equilibrium as the crystal is cooled.
Enhancement of Long-Wavelength Photoluminescence Due to Heat-Treatment in Si-Doped GaAs
Authors: Suezawa M. , Kasuya A. , Nishina Y. , Sumino K. 
Published: September 2012

ABSTRACTHighly officient radiative recombination even at room temperature was found at a wavelength of about 1.3 μm in heat-treated Si-doped GaAs. The range of Si concentrations and the condition of heat-treatment to yield this intense luminescence were determined. Excitation spectra of the PL lines suggest that such PL lines are related to pairs of Si-donor and Si- acceptor and such pairs combined with gallium vacancies.
Formation Mechanism and Recombination-Enhanced Dissociation of a Hydrogen-Carbon Complex in Silicon
Authors: Kamiura Yoichi , Hashimoto Fumio , Yoneta Minoru 
Published: September 2012

ABSTRACTWc have found that chemical etching induced an electron trap E3 (0.15) into n-typc Si. We attribute this trap to a hydrogen-carbon complex on the basis of available experimental data. By measuring DLTS depth profiles of the E3 trap, we propose a model of the formation mechanism of the hydrogen-carbon complex as follows. Hydrogen atoms arc adsorbed on the Si surface to terminate Si dangling bonds during chemical etching, and after the etching some unstably adsorbed ones diffuse into the near-surface region of silicon and are trapped by carbon to form the complex. The E3 trap is stable up to 100δC in the dark but is annihilated by the illumination of band gap light around 250K only outside the depletion layer of the Schottky structure. This provides unambiguous experimental evidence for the recombination-enhanced dissociation, in which the electronic energy released by the electron-hole recombination at the E3 level is converted into local kinetic energy of hydrogen to be released from carbon.
Process Physics of the Iron-Boron Pair Recombination and Dissociation in p-Type Silicon
Authors: Wuaranakula W. 
Published: September 2012

ABSTRACTThe process physics of the iron-boron pair recombination and dissociation in p-type silicon at temperatures below 300°C was studied. The result indicates that the recombination and dissociation processes depend strongly upon the relative position of the ionization energy of interstitial iron Efe+ and the Fermi level Ef. At temperatures T < (Efe+ - Ep)/k, the pairing reaction obeys first-order reaction kinetics while at temperatures T > (EFe+ - Ep)/k, an equilibrium between neutral and charged defect species prevails.
Evidence for Metastabile State of DX Center in AxGa1-xAs
Authors: Ghosh Subhasis , Kumar Vikram 
Published: September 2012

ABSTRACTPhoto-Deep Level Transient Spectroscopy with 1.38 eV light reveals a new level with thermal activation energy 0.2 eV of DX centers in silicon doped Alx Ga1-xAs (x = 0.26) for the first time. The observation of this level directly proves the negative-U properties of DX centers and the existence of thermodynamically metastable state DX.
Defect- Impurity Interaction in Irradiated n-GaAs
Authors: Kdrshunov F. P. , Prokhorenkd T. A. , Sobolev N. A. , Mjdriavtseva E. A. 
Published: September 2012

ABSTRACTThe creation of radiation defects (RD's) and their interaction with shallow impurities in 3–4 MeV electron irradiated n-GaAs have been studied by means of photoluminescence (PL) and Hall effect. The irradiations were carried out at sample temperatures ranging from Ti = 30 to 500°C. It has been found for the first time that for high fluences at room temperature the shallow donor concentration starts to decrease. The behaviour of the carrier concentration (n), mobility (μ)and of the concentrations of the shallow acceptors C (As) and Ge (As) has been studied on irradiation and annealing. It was found that the behaviour of the As vacancy govern the main annealing processes observed.
Metallic Impurities in n- and p- Type Silicon: Dlts Studies
Authors: Agarwal Aditya , Radzimski Z. J. , Buczkowski A. , Shimura F. , Rozgonyi G. A. 
Published: September 2012

ABSTRACTDeep level majority and minority carrier traps in p+/n and n+/p junction diodes have been investigated. The junctions were fabricated on n- and p- type silicon which was intentionally and uniformly doped with heavy metals Cr, Fe, Ni, and Au during Czochralski crystal growth. The activation energies of the traps in these devices has been determined using a computer based Deep Level Transient Spectroscopy system which stores and analyzes entire capacitance-time transients. The capacitance-time data sets have been analyzed using the standard rate-window method as well as by a new algorithm which is able to test for the existence of a single exponential. The new algorithm has shown that only one of the ten traps measured contained a single exponential. Rate-window analysis of all the data sets, however, yielded energy levels based on the expectation of a single-exponential, despite the inherent non-exponentiality of the transients. Implications on the reliability of results obtained by the rate window method have been discussed. Possible reasons for the observed non-exponentiality in the data have been suggested based on a study of simulated data.
The Influence of Stresses on the Surface-Near Defect Structure
Authors: Reiche M. , Nitzsche W. 
Published: September 2012

ABSTRACTAn external stress field, induced at the film edge of a nitride layer, affects the defect generation in the surface-near region. Nucleation and growth of oxide precipitates and/or the generation of dislocations result in the reduction of the width of the denuded zone. The defect formation is discussed in dependence on the stress, gettering technique (annealing conditions), and on the initial oxygen concentration. The effect on electrical parameters is shown. The investigations prove that an additional oxide film (SiO2/Si3N4 films) does not relax completely the tensile stress induced by the nitride layer.