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Defect interactions among oxygen, carbon, and nitrogen during a three‐step high‐low‐high intrinsic gettering process (1100 °C+750 °C+1000 °C) were studied using differential analysis of Fourier transform infrared (FTIR) absorption spectra of Czochralski‐Si crystals intentionally doped with carbon and nitrogen. Two phenomena related to nitrogen were observed: (1) Nitrogen‐enhanced oxide nucleation in the temperature range from 750 to 1100 °C, thus having a negative effect on the denuding step; and (2) defect interaction associated with carbon during oxygen precipitation was significantly affected by the co‐existence of nitrogen. For the latter effect the first‐step annealing at 1100 °C was crucial. The results presented are consistently interpreted assuming that nitrogen participates in creation of nucleation sites for heterogeneous oxygen precipitation, and also assuming that nitrogen aggregates at the strain regions surrounding precipitates and thus retards Si self‐interstitial migration. This explanation was supported by observed differences in oxygen‐precipitate‐related FTIR absorption and by the behavior of stress‐related photoluminescence D lines.

Large amplitude current oscillations with a thermally activated frequency and thermally — stimulated current oscillations were observed in semi-insulating GaAs for the first time. These oscillations were found at DC electric fields above 500 Vcm−1, about one order of magnitude below the electric-field threshold for Gunn oscillations. The activation energy of the oscillation frequency was found to be 0.8 eV corresponding to the dominant electron trap energy in semi-insulating GaAs (the so-called EL2 level recently attributed to the antisite arsenic [1]). A model proposed to explain the phenomena of voltage — controlled negative resistance in semi-insulating GaAs exposes the role of EL2 defect in the trapping process. The capture of electrons from the conduction band by the EL2 defect has a configurational barrier of approximately 70 meV. The presence of an electric field enhances this electron capture process which makes possible the migration of slow domains.

A systematic Fourier‐transformed infrared‐spectroscopy study of oxygen and carbon in isolated form and as complexes in the silicon lattice has revealed a direct correlation between the decrease of substitutional carbon concentration and the decrease of interstitial oxygen concentration during 750 °C annealing. At a concentration exceeding 2 ppma, carbon was also found to enhance oxide precipitate growth. After completing a three‐step annealing (1100 °C+750 °C+1000 °C), an oxide‐precipitate‐related IR‐absorption band was observed. The changes of the IR‐absorption band were correlated with annealing‐induced changes in the state of carbon. A direct incorporation of carbon into oxide precipitates, and/or carbon interaction with silicon self‐interstitials generated during oxygen precipitation, are suggested to have an effect on reducing lattice strain associated with the oxygen‐precipitation process.

The thermodynamic as well as the dynamic constitutional supercooling criteria are derived for liquid phase electroepitaxy (LPEE) taking into account the Peltier effect and electromigration which control the growth interface temperature and mass transport in the solution, respectively. It is shown that solute transport by electromigration enhances significantly the interface stability during growth. Thus the present treatment explains the experimentally attained stable electroepitaxial growth with velocities as high as 25 μm/min. Furthermore, it defines the geometry of the LPEE configuration and the growth parameters (current density and polarity, temperature and substrate characteristics) which lead to the optimization of surface morphology.

A photoluminescence, photocapacitance, and thermal annealing study of Ga‐rich GaAs has revealed the complex behavior of acceptor levels at 68–77 and 200 meV above the valence band. The concentration of all levels is enhanced by Ga‐rich growth conditions, however, only the 77‐ and 200‐meV levels formed preferably in n‐type GaAs are consistent with a double‐acceptor model of the gallium antisite defect. In p‐type GaAs the 68‐meV level associated with a different single‐acceptor defect is dominant. It is argued that the inhibited formation of double‐acceptor GaAs defects in p‐type crystals is caused by the Fermi‐energy control of the defect formation.

The generation kinetics of thermal donors at 450 C in Czochralski-grown silicon was found to be altered by high-temperature preannealing (e.g., 1100 C for 30 min). Thus, when compared with as-grown Si, high-temperature preannealed material exhibits a smaller concentration of generated thermal donors and a faster thermal donor saturation. A unified mechanism of nucleation and oxygen diffusion-controlled growth (based on solid-state plate transformation theory) is proposed to account for generation kinetics of thermal donors at 450 C, in as-grown and high-temperature preannealed Czochralski silicon crystals. This mechanism is consistent with the main features of the models which have been proposed to explain the formation of oxygen thermal donors in silicon.

A comparative study was carried out on the defect structure and electronic properties of layers grown under similar conditions by electroepitaxy (electromigration controlled) and by thermal LPE. It was found that the density of certain microdefects, commonly present in layers, is significantly smaller (about an order of magnitude) in electroepitaxially grown than in thermally grown layers. It was also found that electroepitaxial layers exhibit greater carrier mobility and diffusion length than the thermally grown layers; in addition, electroepitaxially grown p‐n junctions exhibited lower saturation current than the thermally grown junctions. The differences in the characteristics of two types of layers are attributed to corresponding differences in the nature of the driving forces for growth.

Presentation d'une nouvelle methode de croissance de HgCdTc a partir de solutions. Developpement d'un modele de cinetique de croissance utilise pour interpreter les variations de la vitesse de croissance, de l'epaisseur de couche et de la composition de surface avec le temps de croissance, le niveau de la solution et la pression appliquee

A model for electron mobility in a two-dimensional electron gas confined in a triangular well was developed. All major scattering processes---i.e., deformation potential and piezoelectric acoustic, polar optical, ionized impurity, and alloy disorder---were included as well as intrasubband and intersubband scattering. The model is applied to two types of modulation-doped heterostructures, namely GaAs-GaAlAs and ${\mathrm{In}}_{0.53}$${\mathrm{Ga}}_{0.47}$As-${\mathrm{Al}}_{0.52}$${\mathrm{In}}_{0.48}$As. In the former case phonons and remote ionized impurities ultimately limit the mobility, whereas in the latter, alloy disorder is a predominant scattering process at low temperatures. The calculated mobilities are in very good agreement with recently reported experimental characteristics for both GaAs-${\mathrm{Ga}}_{1\ensuremath{-}x}{\mathrm{Al}}_{x}\mathrm{As}$ and ${\mathrm{In}}_{0.53}$${\mathrm{Ga}}_{0.47}$As-${\mathrm{Al}}_{0.52}$${\mathrm{In}}_{0.48}$As modulation-doped heterostructures.

It is found that the rate of the photoinduced transition of the GaAs midgap level EL 2 to its metastable state increases as its occupation increases. High-resolution optical spectra of this transition exhibit a sharp peak very similar to the no-phonon line of the intracenter absorption of the As antisite defect. These findings show that the transition to the metastable state is initiated from the ground state 1A1, and it is finalized via the excited state 1T2 of the neutral As antisite defect. They thus provide a new basis for the critical assessment of the EL 2 metastability models and further confirmation of the association of EL 2 with the isolated As antisite defect.

Oxygen microsegregation and swirl defect formation in Czochralski‐grown silicon were studied by employing interface demarcation, spreading resistance measurements, infrared absorption, high resolution etching, and x‐ray topography. It was found that for forced convection conditions of growth, oxygen segregation is microscopic growth rate‐controlled. Maxima in oxygen concentration occurred at minima in the microscopic rates indicating that the segregation coefficient of oxygen is greater than 1. The distribution of swirl defects was found to be critically dependent on the amplitude of the microscopic growth rate fluctuations; this dependence made it possible to show that the critical impurity nuclei are not related to oxygen but to some impurity, most likely carbon, having a segregation coefficient less than 1.

Nearly perfect indium antimonide single crystals were studied by x‐ray anomalous transmission using silver Kα radiation and {220} reflections. The depth of abrasion‐induced surface damage was determined using the diffracted integrated intensities. The depth of damage was found to be greater on the B than on the A surfaces for the same amount of abrasion. For unidirectional abrasion the direction of the strain corresponded to the direction of abrasion, but some directional strain was also present when the abrasion was not unidirectional. The measured rocking curve half‐widths were not affected by severe surface abrasion. The effective absorption coefficient was measured to be 10.3 ± 1 cm−1.

Cleaved germanium surfaces, oxygenated at room temperature, were heated under high vacuum and the restoration of their oxygen‐adsorbing capacity was determined. No restoration was observed at 425°C. Above 575°C, however, the oxygen‐adsorbing capacity of the surfaces was completely recovered. Discharge of GeO from the surface was associated with this process. The restoration process followed first‐order reaction kinetics with an activation energy of 56 kcal/mole. Concurrently with restoration a pronounced decrease in the surface area was observed. The results are discussed in terms of the kinetic and energy requirements of the system.

The critical temperatures, Tc, and critical current density, Jc were measured for ZrV alloys containing 6 and 9 at% V at various stages of aging at 500 °C. The microstructure of the samples was determined by metallographic and X-ray diffraction techniques in conjunction with previously reported studies. The alloys were found to contain mixtures of martensite α′, complex (h.c.p.) ω and retained (b.c.c.) β phases. Aging resulted in the transformation of these phases to the equilibrium phases, (h.c.p.) Zr-rich α, and the superconducting (at 4.2 °K) intermetallic compound V2Zr. The Tc and Jc results are interpreted in terms of the flux pinning capabilities of the resulting microstructures. Die kritischen Temperaturen Tc und die kritische Stromdichte Jc wurden an ZrV Legierungen mit 6 und 9 At% V in verschiedenen Alterungszustanden bei 500 °C gemessen. Die Mikrostrukturen der Proben wurden mit metallographischen Methoden und Rontgenstreuung in Verbindung mit fruher berichteten Untersuchungen bestimmt. Es wurde gefunden, das die Legierungen Mischungen von Martensit α′-, komplexen (h.d.p.) ω- und ubriggebliebenen (k.r.z.) s-Phasen enthielten. Alterung bestand in der Transformation dieser Phasen zu den Gleichgewichtsphasen: der (h.d.p.) Zr-reichen α-Phase und der (bei 4.2 °K) supraleitenden intermetallischen Verbindung V2Zr. Die Tc- und Jc− Ergebnisse werden mit der Moglichkeit der Flusfestsetzung der resultierenden Mikrostrukturen interpretiert.

Fast neutron irradiation effect on niobium nitride current carrying capacity, showing enhancement

We found that a three‐step high‐temperature annealing leads to intrinsic gettering in oxygen‐lean Czochralski silicon grown in a magnetic field as well as in oxygen‐free float zone silicon. Such thermal treatment has been used thus far for achieving intrinsic gettering only in oxygen‐rich Czochralski silicon. We present experimental characteristics of this new intrinsic gettering process, and we propose a phenomenological explanation involving outdiffusion and precipitation of silicon interstitials rather than oxygen which is involved in the standard intrinsic gettering.

Current oscillations thermally activated by the release of electrons from deep levels in undoped semi‐insulating GaAs were observed for the first time. They were attributed to electric field‐enhanced capture of electrons by the dominant deep donor EL2 (antisite AsGa defect). This enhanced capture is due to the configurational energy barrier of EL2, which is readily penetrated by hot electrons.

The key electronic characteristics of semi‐insulating GaAs, i.e., the Fermi energy, concentration, and occupancy of the midgap donor EL2, and the net concentration of ionized acceptors can all be determined from high‐resolution measurements of the EL2 intracenter absorption. The procedure is based on the measurement of zero‐phonon line intensity before and after the complete transfer of EL2 to its metastable state followed by thermal recovery. The procedure is quantitative, involves no fitting parameters, and unlike existing methods, is applicable even when a significant part of the EL2 is ionized.

Presentation de resultats sur la croissance de couches de HgCdTe par electroepitaxie a partir de solutions riches en tellure a 501°C

A dominant hole trap has been identified in p-type bulk GaAs employing deep level transient and photocapacitance spectroscopies. The trap is present at a concentration up to about 4 x 10 to the 16th per cu cm, and it has two charge states with energies 0.54 + or - 0.02 and 0.77 + or - 0.02 eV above the top of the valence band (at 77 K). From the upper level the trap can be photoexcited to a persistent metastable state just as the dominant midgap level, EL2. Impurity analysis and the photoionization characteristics rule out association of the trap with impurities Fe, Cu, or Mn. Taking into consideration theoretical results, it appears most likely that the two charge states of the trap are the single and double donor levels of the arsenic antisite As(Ga) defect.

Te-doped inSb single crystal growth in transverse magnetic fields, using Czochralski crystal puller

A new phenomenon is reported whereby illumination (in the visible spectrum) is converted into mechanical strain (elastic deformation or mechanical vibrations) in CdS wafers with an orientation perpendicular to the crystallographic axis [001]. It is believed that the light modulates the electric field at the surface (surface barrier) and causes an elastic strain due to the converse piezoelectric effect.

p‐type conduction in (000l)‐oriented CdS films sputtered in the presence of phosphine was observed. dc Hall measurements are presented and p‐n junction characteristics are shown.

The superconducting resistive critical field Hr of the bcc region of the Ti–Nb–V ternary system has been studied. Measurements at 4.2°K on cold‐rolled alloys at 10 at.% composition intervals determined that Hr varied smoothly with composition. A maximum in Hr occurred at a valence electron to atom ratio n of 4.4 for pseudobinaries of the system. The ratio of critical field to transition temperature was found to be a function of n alone in qualitative accord with the theory for type II superconductors. A criterion for predicting the behavior of similar systems is presented.

Superconducting transition temperature variation in bcc region of Ti-Nb-V ternary alloys measured as function of valence electrons and composition

Crystal growth and segregation were investigated in a confined vertical melt zone in which the upper solid-melt interface advanced under destabilizing and the lower interface under stabilizing thermal gradients. A technique reported by Kim et al. (1972) was used in the study. The experimental results are discussed, giving attention to interface morphology and growth rate and questions of dopant segregation. Dopant inhomogeneities formed simultaneously in both advancing interfaces can be explained on the basis of pressure induced segregation effects.