摘要:

The growth of copper precipitate colonies in high‐purity dislocation‐free silicon single crystals has been examined by transmission electron microscopy. The colonies, being coplanar arrangements of copper‐silicide particles on either {110} or {100) planes, nucleate and grow during rapid cooling from higher temperatures. The kinetics of the colony growth process has been analyzed in terms of a model based on repeated nucleation on a climbing dislocation. The possibility of having the growing copper‐silicide particles dragged by the dislocations has been discussed, and a mechanism based on a particle dragging/dislocation climb effect has been suggested in order to explain the development of dendritic dislocation dipole branches.

ISSN:0021-8979    

DOI:10.1063/1.1662820

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Results of analysis of photovoltaic effect in ap‐njunction arising out of the two‐photon process in the presence of a constant built‐in field are presented. The short‐circuit current, the open‐circuit voltage, and efficiency of typical GaAs cells exposed to 1.17‐eV photon flux from a laser are computed. It is shown that marked improvement in the short‐circuit current and efficiency with considerable saving in material are possible with a field of the order 100 v/cm. The effect of reflection at the back face are also discussed and the possible improvement in performance with a reflecting coating of the face estimated.

ISSN:0021-8979    

DOI:10.1063/1.1662821

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

We have developed a compensation method for measuring the reflectivity of flat highly reflecting dielectric mirror coatings with the help of a laser beam. Using two coupled cavities it is possible to determine the reflectance of a spot with the diameter of the laser beam with an accuracy of about ± 3 × 10−5. The method also allows the measurement of the relative distribution of reflectance over the surface of a single mirror. Here the accuracy is equal to the sensitivity of the method, which is ± 2 × 10−5.

ISSN:0021-8979    

DOI:10.1063/1.1662822

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The index of refraction forn‐type GaAs is calculated as a function of photon energy by a method which accounts for the contribution of the fundamental absorption edge to the index of refraction. The absorption coefficient forn‐type GaAs near the band‐gap energy is determined from experimental data; free‐carrier absorption is not included in the calculations; however, its contribution to the index of refraction is estimated to have a negligible effect compared to that due to the fundamental edge. Some applications to single‐ and double‐heterojunction (AlGa)As&sngbnd;GaAs laser structures are discussed. The results indicate that occasionally the most important factor contributing to radiation confinement to the optical cavity in laser structures is the index‐of‐refraction change due to the differences in doping of various regions. Index calculations are made by using absorption data on GaAs at 77 and 300°K. The difference in the index of refraction of a material with different doping can be pronounced. For example, an index change of 1.3% occurs due to differences in the absorption edge of crystals with dopingsn= 2 × 1016cm−3andn= 6.5 × 1018cm−3at an energy of 1.48 eV andT= 77°K. However, the same crystals had a 0.89% index differential atE= 1.37 eV andT= 300°K. These calculations agree extremely well with the index‐of‐refraction differentials determined from radiation pattern characteristics of laser devices.

ISSN:0021-8979    

DOI:10.1063/1.1662823

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

The absolute signs and magnitudes of the second‐order nonlinear optical coefficients,d14, of CuCl, CuBr, and CuI have been determined with laser fundamentals at 1.32, 1.06, and 0.95 &mgr;m. All threed14's are real, negative, and show no dispersion over the measured spectral range. Except for CuI, the magnitudes ofd14are in agreement with data at 1.06 &mgr;m reported earlier by Chemlaet al.The negative signs and magnitudes ofd14most likely require important Cu 3delectron contributions for their explanation.

ISSN:0021-8979    

DOI:10.1063/1.1662824

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Electro‐optic intensity modulation is demonstrated in three‐dimensional (channel) waveguides fabricated by diffusion techniques in ZnSe and CdS. Typical diffused guide dimensions are 1.6 &mgr;m × 19 &mgr;m × 2 mm. Two electrode configurations giving two field orientations are used. Waveguide modulators withV&pgr;(voltage for &pgr; radians phase shift) of 72 V with rise times less than 5 nsec are described. Waveguide modulation in epitaxial layers of ZnS and ZnSe on GaAs is also described.

ISSN:0021-8979    

DOI:10.1063/1.1662825

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Studies of space‐charge‐limited currents as a function of sample thicknessLwere made for CdS and naphthalene monocrystals. In naphthalene, where the current‐voltage curves show the behavior expected for a discrete trap energy above the Fermi level, we findVTFLessentially independent ofL. We attribute this result to the presence of few filamentary regions oriented along thecaxis and differing only slightly from the bulk in distribution of defects. For CdS we findVTFL∝L, consistent with a constant upper field limit of 1.6 × 104V/cm on a one‐carrier injection current. In neither material can the volume concentration of traps be determined from the voltage at which the current rises sharply.

ISSN:0021-8979    

DOI:10.1063/1.1662826

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

An investigation of the effects of 10.6‐&mgr;m laser radiation on triglycine‐sulfate (TGS) crystals determined that the primary irreversible damage mechanisms in TGS pyroelectric detectors are cracking and thermal decomposition (charring). Irradiation thresholds for cracking and charring were determined for TGS crystals of typical detector dimensions as a function of laser power density and irradiation time. These energy density thresholds exhibit two distinct regions of behavior: For short irradiation timesE0is independent of &tgr; while for long timesE0varies as &tgr;1/2. The thresholds are given empirically byE0(crack) = [0.65 + 22(&tgr;)1/2] J/cm2andE0(char) = [4.0 + 34 (&tgr;)1/2] J/cm2. A theoretical model describing thermally induced damage in irradiated crystals is presented. The energy density damage thresholds obtained from this model are compared to the experimental results. These results on material damage are used to predict damage thresholds in operating TGS detectors. These predictions are in good agreement with experimentally determined detector thresholds.

ISSN:0021-8979    

DOI:10.1063/1.1662827

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Monte Carlo calculations of the drift velocity and mean energy vs electric field inn‐type GaAs with a superlattice are reported. The model allows for phonon scattering, and a simple sinusoidal band shape in the direction of the superlattice is assumed. Negative differential mobility and energy saturation appear, and their variation with lattice temperature and miniband width is discussed. The threshold field decreases and the absolute value of the differential mobility increases with decreasing lattice temperature, while the miniband width has minor influence on these parameters. Schockley streaming is observed at low lattice temperature.

ISSN:0021-8979    

DOI:10.1063/1.1662828

出版商:AIP    

年代:1973

数据来源: AIP

摘要:

Energy deposition techniques are applied to the analysis of gas lasers. Using the latest available electron impact cross sections for molecular hydrogen, efficiencies for depositing energy in various excited states are computed. These results, together with the laser rate equations, are used to predict population inversions and emissions in the Werner bands of molecular hydrogen for a laser pumped by 400‐keV electrons. Reasonable qualitative agreement with experiment is obtained.

ISSN:0021-8979    

DOI:10.1063/1.1662829

出版商:AIP    

年代:1973

数据来源: AIP