摘要:

We discuss the possible intrinsic limitation on the temperature dependence of threshold current of long wavelength InGaAsP quantum well lasers caused by Auger recombination and intervalence band absorption. A model calculation of the various band‐to‐band Auger rates are presented. We find that the Auger rates increase with decreasing band gap and also with increasing temperature as in the case of bulk semiconductors. The temperature dependence and the band‐gap dependence arises from the energy and momentum conservation (in the direction normal to the well) that the four particle states involved must satisfy. The estimated Auger coefficient is large enough to be important in single quantum well lasers. However, the Auger effect should be much smaller in a multiquantum well laser than for a single quantum well laser. This is because the carrier density at threshold is smaller (by a factor of 3 to 4) for multiquantum well lasers than for single quantum well lasers. The increased intervalence band absorption with increasing temperature in the active layer may not be responsible for increased threshold current of single quantum well lasers.

ISSN:0021-8979    

DOI:10.1063/1.332185

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Degradation modes due to dark defects under accelerated aging for InGaAsP/InP double heterostructure lasers are investigated by monitoring pulse threshold current, leak current, absorption coefficient, gain factor, and electroluminescence topograph. Most of the dark defects are dark spot defects (DSD’s) and there are only few ⟨100⟩ dark line defects. At the initial stage of the degradation, these dark defects scarcely absorb the emitted light, and the reduction of gain factor causes the increase of pulse threshold current. After this stage, dark defects begin to act as absorber of the emitted light. The generation time of such DSD’s strongly depends on the injected current density but only weakly on the junction temperature in the range of 25 ° to 250 °C. The activation energies for the generation time of the first dark spot defect and the growing speed of ⟨100⟩ dark line defects are estimated to be 0.16 and 0.2 eV, respectively.

ISSN:0021-8979    

DOI:10.1063/1.332186

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Second harmonic radiation at 70 GHz was generated using a 35‐GHz magnetron in bulk ferroelectric LiNbO3and LiTaO3located in a rectangular waveguide. The measured second harmonic output was comparable to theoretical predictions with peak powers as high as 9.8 W for LiTaO3and 7.6 W for LiNbO3for an input power of 24 kW. The output power varied periodically as a function of the sample length due to cavity resonance effects.

ISSN:0021-8979    

DOI:10.1063/1.332187

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

The optical characteristics of Sb2Se3and Sb2Te3films are changed due to an amorphous‐crystalline phase transition below 200 °C. The respective reflectivity of 400 A˚ Sb2Se3and 300 A˚ Sb2Te3films, each on a Te reflective layer, is increased from 10% to 30% and from 45% to 65% by laser radiation. Using these new materials, optical disc recording of FM video signals by a diode laser has been demonstrated.

ISSN:0021-8979    

DOI:10.1063/1.332188

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Quantum counter action has been demonstrated at 10 &mgr;m. A LaBr3:Sm crystal shows a detectivity of 6.7×107cm Hz1/2/W in the 9.6–10.3 &mgr;m region. The same crystal system is also sensitive to infrared radiation in several other bands between 2 and 10 &mgr;. The relative sensitivity for different wavelengths is in agreement with the absorption strengths of the samarium transitions involved. By using a single laser pump line but switching input filters this multicolor sensitivity was used to determine the temperature of the blackbody target used. At very high pump powers there is a large increase in fluorescence output. This output is the result of a ‘‘photon avalanche’’ effect similar to that recently discovered in LaBr3:Pr. The slow buildup and rapid decay of this output provides strong evidence that a multi‐ion process is involved.

ISSN:0021-8979    

DOI:10.1063/1.332189

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

A monolithic surface acoustic wave (SAW) resonator operating at 156 MHz, in which the frequency controlling element is a Fabry–Perot type of SAW resonator and the gain element is a monolithic SAW amplifier (SiOx/InSb/SiOxstructure located inside the SAW resonator cavity) is described and experimental details presented. Based on the existing experimental data, an uhf monolithic ring resonator oscillator is proposed.

ISSN:0021-8979    

DOI:10.1063/1.332190

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Intense extreme ultraviolet (XUV) radiation has a variety of research and production applications. Emission in the 30–300 A˚ range has been measured from noble gas plasmas created by puffing gas into the Pithon electron beam generator at Physics International Co. Spectral, spatial, and temporal measurements from neon, argon, krypton, and xenon plasmas show that sufficient radiation is produced for several applications.

ISSN:0021-8979    

DOI:10.1063/1.332191

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Computer simulations of microwave coupling to a nitrogen‐breakdown plasma have been performed at 25 Torr. Nonhydrodynamic ionization fronts are observed to propagate toward the radiation source under a variety of circumstances. Free‐nitrogen‐breakdown simulations in a spherical system show the propagation velocity of the breakdown wave can be as high as 5×106cm/sec. An elementary theory is used for estimating the speed of the breakdown wave in one dimension. The results are in reasonable agreement with breakdown experiments.

ISSN:0021-8979    

DOI:10.1063/1.332192

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Some results obtained during the etching of Si or the deposition of fluorocarbon films over Si substrates uncoupled from ground in rf plasmas fed with CF4–H2, C2F6–H2, C3F8–H2and CF4–C2F4mixtures are presented. The polymerization process is explained on the basis of a mechanism which involves CF and/or CF2radicals as building blocks as well as an activation of the polymer surface by means of charged particle bombardment. It is definitively proved that the etch rate of Si depends only on the F‐atom concentration, independent of conditions in the various feeds.

ISSN:0021-8979    

DOI:10.1063/1.332193

出版商:AIP    

年代:1983

数据来源: AIP

摘要:

Measurements have been made of the current circulating through a plasma and an adjacent electrically isolated conductor containing an electron‐emitting surface region. This ‘‘unipolar’’ current (so called since it requires only a single electrode) was measured in a dc mercury–argon positive column plasma (7 mTorr Hg, 3 Torr Ar, 1.8 cm radius, 400 mA). The unipolar conductor consists of metal disks located at the boundary of the plasma; these disks include indirectly heated dispenser cathodes which act as the electron‐emitting regions, providing external control of the emission level. The disks can be connected externally in various combinations to form a conductor of variable distribution and area or they can be used as independent electrostatic probes. Measured unipolar currents are in good agreement with values predicted from individual experimental probeV‐Icharacteristics for the disk emitters and collectors, demonstrating that the unipolar current circulation process can be interpreted in terms of electrostatic probe characteristics.

ISSN:0021-8979    

DOI:10.1063/1.332194

出版商:AIP    

年代:1983

数据来源: AIP