摘要:

The pure element secondary ion yields under oxygen and cesium ion bombardment are shown to be solely dependent on a) the ionization potential (or electron affinity for negative ionization) of the sputtered atom and b) the reciprocal of the matrix sputtering yield which determines the equilibrium concentration of implanted oxygen or cesium. This unified approach accounts for the yields of C±, Si±, Ge±and Sn±from the pure elements as well as of Ga±and As±from gallium arsenide.

ISSN:0003-6951    

DOI:10.1063/1.90466

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Transient photocurrent measurements in anthracene crystals and surface potential decay measurements in polyethylene and phthalocyanine films show that care must be taken when applying the normalized logI‐vs‐logtplot of the Scher‐Montroll model to determine transit times. In all three materials, two intersecting straight lines were obtained in the featureless time region beyond previously measured transit times. It is suggested that for the particular fields and thicknesses of samples used, the transit time may be too short to observe by the particular experimental method used, or that the carriers may never reach the rear electrode. In both cases featureless decay curves will be observed, and the logI‐vs‐logtplot can predict erroneous results. Universality seems to be generally obeyed.

ISSN:0003-6951    

DOI:10.1063/1.90467

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The spin polarization of photoelectrons emitted from optically pumped negative electron affinity GaAs shows a systematic depolarization. This is attributed to the spin‐flip scattering at the Cs‐O‐Cs overlayer. The photoexcited electrons thermalize to the &Ggr; point prior to their escape and hence go through the overlayer with the same kinetic energy resulting in photon‐energy‐independent polarization loss.

ISSN:0003-6951    

DOI:10.1063/1.90468

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

It has been demonstrated that the concentration‐dependence curve of cathodoluminescence provides us with a new tool for studying the statistical results of the motion of the mobile carriers in crystals. The experimental results reveal the nonlinear dependence on the activator concentration, suggesting an unknown motion of the mobile carriers in the crystals.

ISSN:0003-6951    

DOI:10.1063/1.90469

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Cr‐MIS solar cells having a 2‐cm2area have been fabricated to produce 12.2% efficiency on single crystal and 8.8% efficiency on polycrystalline Si. Surface‐state data were used to predict open‐circuit voltages of 0.60 and 0.50 V, respectively, for the single‐crystal and polycrystalline Si. Spectral response measurements and Cr metal thickness confirm the differences in short‐circuit current density using these two types of Si.

ISSN:0003-6951    

DOI:10.1063/1.90470

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The amplitude noise of optically pumped cw FIR lasers is drastically reduced by using a FIR ring resonator instead of a linear resonator. Laser emission switches from the clockwise mode to the counterclockwise mode at the FIR line center, a feature permitting precise frequency stabilization of FIR lasers. With an auxiliary retroreflector for one of the modes, unidirectional output occurs across the whole laser tuning width.

ISSN:0003-6951    

DOI:10.1063/1.90471

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A narrow‐band emission has been detected at room temperature during the pulsed on state of a well‐characterized threshold switching material, amorphous Te39As36Si17Ge7P1. The luminescence peak is centered around 0.55±0.03 eV, very close to half of the optical band gap of this material, 1.1 eV. This ratio of luminescence peak to optical band gap is similar to that obtained from the photoluminescence of a large class of chalcogenide glasses in their off states, strongly suggesting that the origins of the on‐state electroluminescence and off‐state photoluminescence are the same. The electroluminescence exhibits a threshold behavior, appearing only for on‐state currents in excess of 4 mA. The output follows a Lambertian law for solid angles up to about 0.7 sr, and slowly deviates below the Lambertian law at larger solid angles. The width of the luminescence line is less than 0.1 eV, indicating that its origin cannot be blackbody radiation. This provides another confirmation of the electronic nature of threshold switching.

ISSN:0003-6951    

DOI:10.1063/1.90472

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Data are presented showing that AlxGa1−xAs (x∼0.42) grown by metalorganic chemical vapor deposition (MO‐CVD) will operate as a photopumped laser to wavelengths as short as ∼6200 A˚ (77 °K). From the different spectral behavior of two separately photopumped epitaxial AlxGa1−xAs (x∼0.36) confining layers (1 and 0.3 &mgr;m thick) with an 80‐A˚ (and a comparison 200‐A˚) GaAs quantum‐well center layer, the recombination of hot electrons with holes collected in the quantum layer is used to estimate &Dgr;Ev.

ISSN:0003-6951    

DOI:10.1063/1.90473

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Ultrashort transients of variable duration have been generated at 10.6 &mgr;m by operating a fast optical switch with picosecond pulses from a mode‐locked Nd : glass laser. The switch, which takes advantage of the large free‐carrier contribution to the infrared optical susceptibility in Ge, has been used to generate megawattt picosecond pulses at 10.6 &mgr;m by synchronous operation of a TEA CO2laser with the 1.06 &mgr;m source.

ISSN:0003-6951    

DOI:10.1063/1.90474

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The electron affinity of oxide semiconductors (In2O3,SnO2, etc.) is a topic of current interest. These materials are capable of forming barrier devices on a number of semiconductors which exhibit good photovoltaic conversion efficiency. We will show that simple methods based on the electrical measurements of oxide‐semiconductor/base‐semiconductor systems often lead to incorrect results, due to the uncertainty in the Fermi‐level position in the oxide‐semiconductors and other interface parameters. To determine the true potential of a particular oxide‐semiconductor, other methods should be used to find the electron affinity.

ISSN:0003-6951    

DOI:10.1063/1.90475

出版商:AIP    

年代:1978

数据来源: AIP