摘要:

The thermal stress in an LED caused by junction heating has been calculated. It is shown theoretically that the change of light output with time is proportional to the third power of thermal stress in the junction. This result is experimentally verified. Mechanical‐stress experiments demonstrate that degradation may occur by means of mechanical stress alone. Using the two‐path model for the quantum efficiency and the time dependence of the stress‐induced lattice‐defect concentration, a degradation formula is derived which can be verified to fit the behavior of many LED’s. The characteristic tapering off seen in most degradation curves can be attributed to strain hardening (dislocation pinning). A dark‐line‐defect progression is observed.

ISSN:0021-8979    

DOI:10.1063/1.326746

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Electron beams propagating in current‐carrying plasma channels proposed for ICF reactors generate an electric field which drives a return current. This electric field reduces the electron energy and also causes an expansion of the trajectory envelope. The scaling of this effect is discussed and estimates of its importance for reactor‐level conditions are presented.

ISSN:0021-8979    

DOI:10.1063/1.326747

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Laser action in singly ionized metal atoms has been obtained when a rare gas is excited in a metal hollow cathode. The required metal‐vapor density is produced by discharge sputtering from the cathode and the excitation of upper levels occurs via a charge‐transfer reaction of the typeB++M→ (M+)+B+&Dgr;E. We present a unified discharge‐sputtering theory which describes the metal density created in the hollow cathode, including both the current and spatial dependence. The predictions of this model are then compared to the measured dependence of metal‐vapor density with current, spatial position, and buffer‐gas pressure. Discharge conditions which support laser oscillation are emphasized. Agreement between theory and experiment is good.

ISSN:0021-8979    

DOI:10.1063/1.326758

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The absorption coefficient of an equilibrium argon plasma is computed, avoiding earlier restrictive assumptions, as a function of temperature and electron density. Our results suggest that the diagnostic applications of resonant absorption to temperature estimates are more difficult than previously expected.

ISSN:0021-8979    

DOI:10.1063/1.326759

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

We present the results of a defect study of liquid‐encapsulated Czochralski grown InP substrates, and InGaAsP grown by liquid‐phase epitaxy using the technique of transmission cathodoluminescence (TCL). The TCL image of the dislocations permits an accurate measurement of the dislocation density and an estimate of the minority‐carrier diffusion length. In addition to the dislocation density, TCL examines material quality by imaging growth‐related defects, e.g., growth striations in InP and stacking faults in InGaAsP.

ISSN:0021-8979    

DOI:10.1063/1.326760

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The trapping of ion‐implanted deuterium (D) by lattice damage in Fe was investigated in the temperature range 90–500 K. The D depth profile was determined by measuring the proton yield from the3He‐excited nuclear reaction D(3He,p)4He, and the D lattice location was obtained by ion channeling. Linear ramping of the temperature produced a sharp detrapping stage at 260 K and a broader release extending over 350–450 K. The release‐vs‐temperature data were analyzed by solving the diffusion equation with appropriate trapping terms, yielding 0.48 and ?0.81 eV for the binding enthalpies associated with the two stages. The 0.48‐eV trap corresponds to D at a near‐octahedral interstitial site, where it is believed to be associated with a vacancy.

ISSN:0021-8979    

DOI:10.1063/1.326761

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Anomalous carrier profiles in BF+2‐ion‐implanted silicon are investigated by theC‐Vand incremental‐sheet‐resistivity methods. An anomalous tail extends about twice as deep as the normal profile, while the peak carrier concentration is around 1/100 that of the main peak. The origin of this anomalous tail is investigated by comparing the profiles of B+, B++F+, and BF+2ions implanted using postacceleration‐ and preacceleration‐type implanters. High‐energy B+ions generated between a mass‐separation magnet and a postacceleration tube are found to be responsible for the observed profiles.

ISSN:0021-8979    

DOI:10.1063/1.326762

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Dislocation slip‐band velocities were measured at 77‐ and 300‐K in well‐ordered Cu3Au single crystals. The results of the 77 and 300 K experiments were very similar: No slip‐band motion is produced at stresses below a critical stress approximately equal to the macroscopic‐yield stress, and bands that were produced during one‐load pulse were never observed to move during subsequent load applications. The slip‐band velocity increases very rapidly in a small stress range above the critical stress.

ISSN:0021-8979    

DOI:10.1063/1.326709

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

The depth profiles of 350‐keV121Sb ions implanted at room temperature into diamonds were determined from neutron‐activation‐layer‐removal experiments. Profiles for both random and aligned (⟨111⟩) implantations were measured. The distribution of antimony ions implanted under channeling conditions was found to be centered somewhat deeper in the crystal than that of Sb ions implanted into a nonaligned diamond. The distribution tail extends in the case of channel implantation far into the crystal, well beyond the region of measurable damage.

ISSN:0021-8979    

DOI:10.1063/1.326710

出版商:AIP    

年代:1979

数据来源: AIP

摘要:

Heterostructures of Pb1−xSnxTe grown by LPE were studied by an etch technique. A consistent pattern appeared in which the lattice‐mismatched heterostructure exhibits a high etch‐pit density (?1×107cm−2) at the interface and in the heteroepitaxial layer. The greater the lattice mismatch, the higher is the defect density. A mismatch as small as ∼2×10−4is already sufficient to generate defects at the interface. A low‐etch‐pit‐density substrate does not moderate the defect performance in the interface and the epilayer. Homostructures show preservation of dislocation etch‐pit density throughout the whole thickness of the epilayer without a substantial decrease, contrary to other reported results. Some differences were found with respect to the opposite heterostructures Pb1−xSnxTe/Pb1−ySnyTe and Pb1−ySnyTe/Pb1−xSnxTe. A high growth temperature (?600 °C) causes a decrease in etch‐pit density and the disappearance of some defects. Enhanced nucleation, annealing of dislocations, and bulk diffusion are believed to take place at the high temperature. Some defects disappear and others diminish upon slow cooling, but the basic mismatch character remains.

ISSN:0021-8979    

DOI:10.1063/1.326711

出版商:AIP    

年代:1979

数据来源: AIP