Showing papers on "Spontaneous emission published in 1972"
Journal Article•
168 citations
TL;DR: The radiative recombination rate in silicon at 300°K was measured as a function of the electron and hole concentration n = p at high injection levels by charge extraction.
Abstract: The radiative recombination rate R in silicon at 300°K was measured as a function of the electron and hole concentration n = p at high injection levels. Carriers were injected in a p-i-n device, and their concentration was measured by charge extraction. The equation R = B n p = B n2 was verified up to n = 2×1017 cm−3 The radiative recombination probability was found to be B = 1.1 × 10−14 cm3/s.
Die Rate R der strahlenden Rekombination in Silizium wurde bei 300°K als Funktion der Elektronen- und Locherkonzentration n = p bei hoher Injektion gemessen. Die Ladungstrager wurden in eine p-i-n-Diode injiziert, und ihre Konzentration wurde durch Ladungsextraktion gemessen. Die Gleichung R = B n p = B n2 wurde bis zu n = 2× ×1017 cm−3 verifiziert. Der Koeffizient der strahlenden Rekombination wurde zu B = 1,1 × 10−14 cm3/s bestimmt.
83 citations
TL;DR: In this paper, an atomic-beam experiment based on momentum transfer between photons and atoms during resonant interaction is described, providing the first direct experimental evidence in the optical region of the isotropic recoil effect in spontaneous emission.
58 citations
TL;DR: In this article, the nonlinear saturation spectrum of parametric instabilities is shown to be restricted to discrete values of the propagation vector if spontaneous emission is neglected and a one-dimensional analysis is used.
Abstract: The nonlinear saturation spectrum of parametric instabilities is shown to be restricted to discrete values of the propagation vector if spontaneous emission is neglected and a one-dimensional analysis is used. The purely growing instability is not excited for equal ion and electron temperatures if the power is less than 3.5 times the threshold power. The inadequacy of the present one-dimensional treatment is pointed out, and it is shown that waves with propagation vectors that are not parallel to the pump field must be present even if spontaneous emission is neglected.
43 citations
TL;DR: In this article, the nonlinear level of Langmuir and acoustic wave fluctuations excited by parametric decay instability, and saturated by induced scattering of the plasma waves from dynamically screened ions (low-frequency spontaneous emission), are calculated.
Abstract: A calculation is presented of the nonlinear level of Langmuir and acoustic wave plasma fluctuations excited by parametric decay instability, and saturated by induced scattering of the plasma waves from dynamically screened ions (low‐frequency spontaneous emission). This is found to be an important weak turbulence saturation mechanism for instabilities excited parametrically in the ionosphere. The cross section for incoherent scattering from the excited waves is obtained and comparisons are made with recent experiments.
43 citations
TL;DR: Four new ir laser bands were discovered and four new stimulated emission lines belonging to the first and second positive systems were obtained and identified as to rotational quantum number.
Abstract: Accurate wavelength measurements in the molecular nitrogen pulsed laser have been made. Four new ir laser bands were discovered. In addition, about two hundred new stimulated emission lines belonging to the first and second positive systems were obtained and identified as to rotational quantum number. An analysis of the possible pumping mechanisms in accordance with experimental results is given.
39 citations
TL;DR: In this paper, the authors investigated different models for the collisional excitation of carbon monoxide (CO) by solving the rate equations for the ten lowest energy levels, including stimulated emission and absorption by 3 K isotropic radiation, spontaneous emission, and collisions.
Abstract: Investigation of different models for the collisional excitation of carbon monoxide (CO) by solving the rate equations for the ten lowest energy levels, including stimulated emission and absorption by 3 K isotropic radiation, spontaneous emission, and collisions. The results are qualitatively applicable to other linear molecules. They show that a wide range of rotational excitation temperatures, including population inversions, can be produced by the various kinetic temperatures and particle densities which are likely to occur in the interstellar regions containing molecules.
38 citations
TL;DR: In this paper, the authors measured the vibrational deactivation time of dye molecules in spontaneous emission in water and methanol and showed that the decay time is 40 ± 5 psec.
32 citations
TL;DR: In this paper, the lasing and spontaneous emission from p+n−n+n+ heterojunction lasers with lightly doped n-type active regions was studied. And it was further shown that the 300 K gain coefficient dependence on the junction current differs greatly from that predicted on the basis of band-to-band lasing involving a parabolic density of states distribution.
Abstract: A study of the lasing and spontaneous emission from p+‐n‐n+ heterojunction lasers with lightly doped n‐type active regions shows that the stimulated emission is not due to a simple band‐to‐band recombination process. It is further shown that the 300 K gain coefficient dependence on the junction current differs greatly from that predicted on the basis of band‐to‐band lasing involving a parabolic density‐of‐states distribution.
25 citations
TL;DR: In this article, the first observation of diode laser action from evaporated thin films of any semiconductor was made, in the pulsed mode with an average current density of (2.3) × 102 A cm−2.
Abstract: Thin‐film diode lasers have been made from Schottky barriers on epitaxial PbTe. At 77 °K the spontaneous emission spectrum agrees with that calculated for direct band‐to‐band transitions. At 12 °K laser action is observed in the pulsed mode with an average current density, at threshold, of (2–3) × 102 A cm−2. This is the first observation of diode laser action from evaporated thin films of any semiconductor.
25 citations
TL;DR: In this article, a two level atom in its excited state, placed in a cavity in which no photons are present initially, and interacting with N modes of the electromagnetic field is solved exactly in the electric dipole, rotating wave approximation.
Abstract: The problem of a single two level atom in its excited state, placed in a cavity in which no photons are present initially, and interacting with N modes of the electromagnetic field is solved exactly in the electric dipole, rotating wave approximation. Expressions for the energy eigenvalues and eigenvectors are derived, and an exact representation for the time dependent wavefunction of the system is given. These quantities are evaluated analytically for N=1,2 and 3, and the time dependent properties of the system for these values of N are investigated and discussed.
TL;DR: In this article, the spontaneous emission behavior of a cw stripe geometry GaAs laser is examined in detail and a sharp discontinuity of spontaneous emission growth occurs when the laser reaches threshold above threshold, coming mostly from the regions where the lasing light intensity is small.
Abstract: The spontaneous emission behavior of a cw stripe‐geometry GaAs laser is examined in detail Contrary to recently published results, a sharp discontinuity of the spontaneous emission growth occurs when the laser reaches threshold Above threshold, slow increases in the spontaneous emission are observed, coming mostly from the regions where the lasing light intensity is small Other discontinuity points were, at higher currents, observed corresponding to the onset of higher‐order modes and second‐order mode locking
TL;DR: In this article, an abrupt reduction in the rate of growth of the spontaneous emission has been observed to occur at the lasing threshold of stripe geometry double-heterostructure injection lasers.
Abstract: An abrupt reduction in the rate of growth of the spontaneous emission has been observed to occur at the lasing threshold of stripe‐geometry double‐heterostructure injection lasers. The observations are contrary to a previously published result of Sommers and imply that increases in the quasi‐Fermi level separation with current are significantly reduced at the lasing threshold in agreement with present theoretical predictions.
TL;DR: In this paper, the current dependence of the spontaneous and coherent intensities and differential intensities from GaAs injection lasers operated at 300 K was investigated and the data were consistent with 100% radiative recombination but do not exclude nonradiative transitions.
Abstract: The current dependence of the spontaneous and coherent intensities and differential intensities from GaAs injection lasers operated at 300 K is reported. A compensated material with single heterojunction and a low‐doped double heterojunction unit were studied. While the spontaneous intensities rise smoothly with current at all power levels, the differential intensities show structure associated with onset of lasing. At threshold there is a sharp cusp, indicating a change in the internal dynamics. The data are found to be consistent with 100% radiative recombination but do not exclude nonradiative transitions. New features are negative differential intensity of lasing; a logarithmic increase of Fermi level with current in the lasing region; and marked differences of the spreading of the lasing spectrum and of the current saturation of the two lasers.
TL;DR: In this article, a line shape analysis of the GaSe spectrum at high excitation intensities is presented, where the spectrum becomes dominated by recombination of an exciton-carrier complex.
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TL;DR: The past decade has seen a rapid improvement in the effectiveness and reliability of VISIBLE-LIGHT-EMITTING DIODES as mentioned in this paper. But, as a result, large-scale MANUFACTURING of DIODS SUITABLE for a variety of applications has become possible.
Abstract: THE PAST DECADE HAS BEEN A DRAMATIC IMPROVEMENT IN THE EFFICIENCY AND RELIABILITY OF VISIBLE-LIGHT-EMITTING DIODES. THE MAJOR PROBLEMS LIMITING THE PERFORMANCE OF THESE DEVICES HAVE BEEN MASTERED AND, AS A RESULT, LARGE-SCALE MANUFACTURING OF DIODES SUITABLE FOR A VARIETY OF APPLICATIONS HAS BECOME POSSIBLE. THEY WILL INCREASINGLY REPLACE OTHER TYPES OF SMALL DISPLAY ELEMENTS IN THE COMING YEARS AS COSTS DECREASE FURTHER. IN ADDITION, LEDS WILL BE USED IN AREAS WHERE OTHER DEVICES ARE IMPRACTICAL BECAUSE OF EXCESSIVE POWER DISSIPATION, BULKINESS, OR INADEQUATE LIFE. AT PRESENT, DIODES THAT EMIT RED LIGHT ARE THE MOST WIDELY USED. BUT NEWER MATERIALS, SUCH AS FOR GREEN EMISSION, FOR YELLOW, AND FOR BLUE, ARE BEING DEVELOPED AND WILL BECOME MORE AND MORE IMPORTANT AS THE MATERIALS PROBLEMS LIMITING THEIR REPRODUCIBILITY ARE OVERCOME. /AUTHOR/
TL;DR: In this article, it was shown that magnetic recombination in copper, excited by an electron beam, has been observed at 2.3, 4.0 and 5.3 eV from transitions between conduction band states near the Fermi level or the Brillouin zone boundaries and d holes.
TL;DR: In this article, the authors examined the possibility of observing effects arising from stimulated emission in the radiative recombination from electron-hole liquid in semiconductors and concluded that the optical gain arising from such stimulated emission would be too small for direct observation.
Abstract: This paper examines the possibility of observing effects arising from stimulated emission in the radiative recombination from electron-hole liquid in semiconductors. It is concluded that the optical gain arising from such stimulated emission in Ge would be too small for direct observation. A technique is proposed which still allows confirmation of stimulated emission by indirect means.
TL;DR: In this paper, the light emission of vapour-grown crystals of CdS was studied under an intense ultraviolet laser light excitation at 4.2°K, and the quadratic dependence of the exciton-exciton emission intensity on the ultraviolet excitation intensity was investigated.
TL;DR: The adoption of the more sensi tive computer analysis techniques in the present work has allowed us to extend this type of measurement down to discharge currents of a small fraction of an ampere and, hence, into a region where a much more pronounced dependence of the Lorentz width on discharge current is obtained.
Abstract: Spontaneous emission profiles of the 3p4p → 3p4s transitions in singly ionized argon have been studied with a scanning, planeparallel Fabry-Perot interferometer. A precision method of analysis was used in which ≈300 uniformly spaced data points were taken digitally across one free-spectral range of the inter ferometer for each set of discharge conditions and reiteratively fit using the method of least squares to a Voight profile as dis torted by the Fabry-Perot. The adoption of this technique has permitted obtaining order-of-magnitude improvement in ac curacy and sensitivity in studies of line breadth parameters over previous, analog methods of analysis.The improvement is especially important in studies of the argon ion laser transitions at the low current limit due to the exponential dependence of the light intensity on the discharge current. The validity of the assumption of a Voigt profile (Gaussian distribution of Lorentzians) in analyzing the spontaneous emis sion line shapes of light emitted in the axial direction on the argon ion laser transitions has been examined previously by Bennett et al. I t should be noted in this regard tha t the currently ac cepted theoretical values for the lower state lifetimes yield nat ural widths on these transitions that are in the order of 500 MHz (see Table I ) and hence are in the regime where negligible distor tion ( < 0 . 5 %) from the Voigt profile approximation should occur due to acceleration of the excited ions within the upper state life time for light emitted in the axial direction of the discharge. As previously reported by Bennett et al. a definite dependence of the Lorentz widths on discharge current is encountered in the range from about 5 A to 10 A. The adoption of the more sensi tive computer analysis techniques in the present work has per mitted us to extend this type of measurement down to discharge currents of a small fraction of an ampere and, hence, into a region where a much more pronounced dependence of the Lorentz width on discharge current is obtained. Fig. 1. Measured Lorentz widths as a function of discharge current at 0.2 Torr filling pressure in a 2-mm diam capillary for the Ar l l 4765-Å line.
TL;DR: In this article, a thermally tuned Q-switched ruby laser has been used to selectively excite the 6939-A transition in a potassium plasma and a burst of intensified spontaneous emission at both 6911 and 6939 A has been observed.
Abstract: A thermally tuned Q‐switched ruby laser has been used to selectively excite the 6939‐A transition in a potassium plasma. A burst of intensified spontaneous emission at both 6911 and 6939 A has been observed. This enhanced emission contains information on the local properties of the plasma as demonstrated by the observed dependence of the signal duration upon the free‐electron density.
TL;DR: In this paper, a method is developed to calculate the electron diffusion length in GaAs electroluminescent diodes from their measured spontaneous emission spectra, based on selective self-absorption in the p-region of the device and on the detailed balance principle.
Abstract: A method is developed to calculate the electron diffusion length in GaAs electroluminescent diodes from their measured spontaneous emission spectra. The technique is based on selective self-absorption in the p-region of the device and on the detailed balance principle. The results of our calculations are a diffusion length of 3.5±1 ωm at 300°K and 0.75±0.25 ωm at 77°K. It is shown that the decrease in the external efficiency with increase in temperature in these diodes is due to both the increase in self-absorption and the decrease of the internal quantum efficiency. It is concluded that the quantum efficiency increases by a factor of about 3.5 to 5 in going from 300 to 77°K.
TL;DR: In this article, the authors measured the variation of quantum efficiency of radiative recombination in the phosphor layer as a function of injected current density and of temperature, which allowed a better understanding of the behavior of diffused SiC diode excited by current flow as well as estimates of some important parameters.
Abstract: From cathodoluminescence measurements on a diffused SiC diode with the p layer removed, it has been possible to measure separately the variation of quantum efficiency of radiative recombination in the phosphor layer as a function of injected current density and of temperature. This has allowed a better understanding of the behavior of a diffused SiC diode excited by current flow as well as estimates of some important parameters.
TL;DR: In this article, the problem of an atom interacting simultaneously with the quantized modes of the vacuum electromagnetic field and with a classical time dependent field is investigated utilizing the general theory of damping devised by Heitler.
Abstract: The problem of an atom interacting simultaneously with the quantized modes of the vacuum electromagnetic field and with a classical time dependent field is investigated utilizing the general theory of damping devised by Heitler. Spectral lineshapes are obtained as a function of the variables of the classical field and are studied in detail for the case of spontaneous emission from coupled levels of dissimilar lifetimes. In the limit that the time dependent coupling vanishes, the resulting spectral line is the same as that derived by Weisskopf and Wigner.
TL;DR: The gain at 10.6 µm in a CO2 laser gas mixture was correlated as a function of discharge current with induced changes in the plasma impedance and spontaneous emission at 2.4 µm and 3576 µm as mentioned in this paper.
Abstract: The gain at 10.6 μ, in a CO2 laser gas mixture, is correlated as a function of discharge current with the induced changes in the plasma impedance and spontaneous emission at 2.4 μ and 3576 A. The r...
IBM1
TL;DR: In this article, the rate equations for carriers injected into an amorphous semiconductor were considered for a simple model with radiative recombination of injected electron and holes and with emission and absorption of optical phonons of a single energy.
Abstract: The rate equations for carriers injected into an amorphous semiconductor are considered for a simple model with radiative recombination of injected electron and holes and with emission and absorption of optical phonons of a single energy. The approximate energy dependence of the rate coefficients is calculated for a model of the band tail states. A steady-state solution of the rate equations is compared with experimental results for luminescence and photoconductivity in amorphous As2Te2Se.
TL;DR: In this article, a comparison of the emission spectra produced under photoexcitation and cathodo-excitation reveals a peak wavelength difference, interpreted in terms of a difference between the effective electron temperature of free electrons for the two modes of excitation.
Abstract: Comparison of the emission spectra produced under photoexcitation and cathodoexcitation reveals a peak wavelength difference. This is interpreted in terms of a difference between the effective electron temperature of free electrons for the two modes of excitation and leads to a brief discussion of possible complications in the interpretations of radiative recombination processes.