摘要:

Chemical sputtering yields of crystalline silicon resulting from mass‐separated, reactive ion bombardments are measured as a function of ion kinetic energy at room temperature. Ions of F+and CFn+(n= 1,2,3) are bombarded independently onto a silicon surface in an ultrahigh vacuum (UHV) environment. Evolution rate of SiF4molecules resulting from surface chemical reaction: Si+4F→SiF4↑, is measured using a quadrupole mass filter. For F+/Si ion bombardment, yield increases monotonically with ion kinetic energy and saturates at 1 keV giving a value of 0.18. For CFn+/Si ion bombardment, yields show maxima at 1200 eV (CF+), 800 eV (CF2+) and 700 eV (CF3+). At ion energy ranges above 1.5 keV, yields for CFn+/Si are about half that for F+/Si. Carbon deposition and scavenging effects are discussed in detail by relating with fluorocarbon ion bombardment.

ISSN:0021-8979    

DOI:10.1063/1.331021

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The system Indium+Mn precipitates has been irradiated with 275 keV Ar+ions at low temperatures (T<15 K). By using the depression of the superconducting transition temperatureTcas a probe for dissolved Mn atoms, it could be demonstrated that an ion‐beam induced precipitate dissolution occurs even at small Ar fluences (<1015cm−2). The maximum amount of Mn atoms which can be forced into metastable solution by irradiation depends on the preparation conditions of the samples. For high Ar fluences the dissolution effect is overlapped by the influence of the simultaneously produced radiation damage onTc.

ISSN:0021-8979    

DOI:10.1063/1.331022

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A nonsubstitutional alloy of 7 at. % Cr implanted in single‐crystal aluminum has been irradiated withQ‐switched ruby laser pulses up to 6 J/cm2. Liquid phase epitaxy, resulting in enhanced substitutionality without any Cr redistribution, is observed up to 2 J/cm2for a laser pulse duration of 25 ns. At higher energy densities and with shorter pulses, 12‐nsec duration, convection effects are observed to inhibit liquid phase epitaxy. The surface reflectance appears to reduce due to high implantation dose.

ISSN:0021-8979    

DOI:10.1063/1.331023

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Transmission and scanning electron microscopy studies of holes created by laser irradiation on Al and Cr films were carried out. The results showed that both films have the well‐shaped round holes and that the peripheral regions form gentle swells for Al films and steep swells for Cr films. From the measurement of surface shape across the groove made by a laser beam the height of swells was nearly the same as the film thickness. It was also found that the swells are composed of large recrystallized grains, and that the effect of the existence of large grains on the recording characteristics is not so evident. The numerical analysis of temperature rise of the metal films was made using the finite difference method considering the phase transition of the film materials. Comparison of the temperature distributions with the experimental results revealed that the hole initiated by vaporization at the center of the melt expands outwards by the surface tension.

ISSN:0021-8979    

DOI:10.1063/1.331024

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A spatially periodic distribution of electron‐hole pairs has been produced in silicon crystals by excitation with a pulsed neodymium yttrium aluminum garnet (Nd: YAG) laser. The diffraction efficiency and the decay time of the grating structure has been measured by diffraction of an independent quasi‐cw laser beam as a function of the energy density of the exciting laser. At low energy‐densities the diffraction efficiency is given by a squared Bessel function dependent on the carrier density as expected from theory. At higher incident energy densities deviations occur which can be explained by free‐carrier absorption and intensity fluctuations across the beam. The grating decay time is determined by ambipolar diffusion and Auger recombination.

ISSN:0021-8979    

DOI:10.1063/1.331025

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Measurements carried out on semitransparent S1 photocathodes which indicate that their surface resistivities depend critically on the processing techniques used are described. The results show that, in general, S1 photocathodes having good long wavelength response (≳1 &mgr;m) exhibit high surface resistivities ∼M&OHgr;/&laplac;. A method is also outlined by which improved near infrared (NIR) photoresponse can be obtained for an Ag‐O‐Cs photocathode, and a physical interpretation is suggested to explain the observed characteristics.

ISSN:0021-8979    

DOI:10.1063/1.331026

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Cadmium doping in vapor phase epitaxial growth of InP has been investigated; a partial pressure of cadmium was produced in an open tube system (In/PC13/H2technique) by heating a cadmium metal source. The characterization of epitaxial layers was carried out over a wide range of doping densities. The distribution coefficient of cadmium was found to be 0.2 for a cadmium partial pressure below 1.5×10−4atm. Above that pressure, a strong compensation limitsNA−NDto a value below 3×1018at. cm−3, while the growth rate decrease from 8 to 3 &mgr;m h−1. The carrier concentration was found to decrease regularly with heat treatment at 300 °C under hydrogen. Photoluminescence measurements have pointed out, in all cases, a broadband emission, centered at 1.3677 eV, corresponding to transition from Cd acceptor levels; however, the near‐edge emission lines, peaked at 1.4105, 1.4115, and 1.4126 eV, in heavily doped layers, vanish upon annealing at 300 °C and are replaced by lines characteristic of lightly doped layers (1.413, 1.4145, 1.417, and 1.4182 eV respectively).

ISSN:0021-8979    

DOI:10.1063/1.331027

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

It is proposed that interfacial reaction barriers in binaryA/Bdiffusion couples lead to the absence of phases predicted by the equilibrium phase diagram, provided that the diffusion zones are sufficiently thin (thin‐filmcase). With increasing thickness of the diffusion zones the influence of interfacial reaction barriers decreases and the simultaneous existence of diffusion‐controlled growth of all equilibrium phases is expected (bulkcase). Selective growth of the first and second phases and the effect of impurities are discussed with the influence of interfacial reaction barriers and with references to the known cases of silicide formation.

ISSN:0021-8979    

DOI:10.1063/1.331028

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Arsenic doped amorphous silicon layers have been deposited on silicon single crystals by rf cathodic sputtering of a silicon target in a reactive argon‐hydrogen mixture, and annealed with aQ‐switched ruby laser. Topographic analysis of the laser irradiated layers indicate that a crater is formed due to an evaporation of material which could be related to the presence of a high concentration of argon in these deposited films. Furthermore, Rutherford Backscattering experiments showed that a highly disordered surface layer is left after irradiation due probably to an inhibition of the recrystallization by the presence of hydrogen as revealed by nuclear reaction analysis. Nevertheless, it was found that below this surface layer arsenic has diffused into the monocrystalline substrate. Therefore, under convenient experimental conditions, (repetitive laser pulses),p‐njunctions of good quality could be formed.

ISSN:0021-8979    

DOI:10.1063/1.331029

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

In conjunction with Auger electron spectroscopy measurements, we have developed a procedure for obtaining a clean Nb surface using an electron bombardment heating technique. We have then studied the valence band photoemission as a function of photon energy. We find that calculations for the bulk theoretical density of states are in basic agreement with the ultraviolet photoemission spectroscopy data. We have also studied the initial oxidation of the clean Nb surface. Structure in the energy distribution curves suggests three stages in the oxidation process. Furthermore, the valence band energy distribution curves for clean Nb3Sn prepared ’’insitu’’ were measured and showed a strong resemblance to pure Nb as has been observed previously in x‐ray photoemission. Evidence is found for the existence of Nb2O5and SnO2in the surface oxides of Nb3Sn.

ISSN:0021-8979    

DOI:10.1063/1.331030

出版商:AIP    

年代:1982

数据来源: AIP