摘要:

The stable gas products of germane dissociation and subsequent radical reactions have been measured in pure germane glow discharges characteristics of the initial germane fragmentation are inferred from these data. The spatial distribution of discharge optical emission, and of film deposition on glass fibers, have also been measured. Finally, the surface reaction probability &bgr; of depositing neutral radicals has been measured to be 0.61±0.09 on the grounded electrode. Major differences between germane and silane discharges occur in all these observables. Possible explanations of these differences are given, but much less chemical data exists for germane, thereby precluding definitive judgments. A probable cause of the normally much poorer semiconductor quality ofa‐Ge:H films, compared toa‐Si:H, is suggested. This is based on the thermodynamics of the H2release reaction at the growing surface.

ISSN:0021-8979    

DOI:10.1063/1.348384

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We have developed a KCl:Li (F+2)Acolor center laser which produces more than 1.2 W of cw laser power, over a factor of 3 greater than the highest power previously reported. This paper contains the results of this study, and presents guidelines for preparing laser crystals to routinely and reproducibly generate these high powers.

ISSN:0021-8979    

DOI:10.1063/1.348385

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We examined chemical state of fluorine doped silica glasses and its thermal behavior. Almost all of the fluorine atoms were found to have the ≡SiF structure with Raman spectroscopy. No optical absorption in the region of 3–9 eV was detected in the glass. When the glasses were annealed in a He atmosphere at 1000 °C, absorption bands peaking at 7.6 and 4.3 eV appeared. These two bands are attributed to the ≡SiSi≡ structure and to F2molecules, respectively. We proposed a thermal decomposition reaction expressed as ≡SiF+FSi≡→≡SiSi≡+F2. The concentrations of the reaction products, ≡SiSi≡ and F2, estimated from the absorption cross sections were equal to each other within the errors of measurements. We also examined the radiation damage with &ggr; ray. The concentration ofE’center was almost the same for the same dose in silica glasses having different concentrations of FSi≡ and ≡SiSi≡. We suggest that FSi≡ and ≡SiSi≡ were found to be stable for &ggr;‐irradiation at room temperature.

ISSN:0021-8979    

DOI:10.1063/1.348386

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

A 1‐cm‐long hollow parylene (C8H8) cylinder‐type target was irradiated with a long pulse CO2laser (400 J/50 ns) to produce a confined soft x‐ray laser source. The amplification of the Balmer‐alpha line (182.2 A˚) of the H‐like carbon was observed using two different gain determination methods. The time‐ and space‐integrated gain coefficient up to 2.2(+0.6/−1.1)cm−1was obtained from the ratio of the axial to transverse line intensity. By using the C8H7Cl target, the gain coefficient increased up to 2.8(+0.6/−1.1)cm−1, inferring the radiative cooling effect. The experimental results agreed with the simulation results within a factor of 5. By reducing the cylinder mass by a factor of 20, the simulation result gave the long gain duration up to 20 ns in FWHM and large gain region up to 1.3 mm in radius.

ISSN:0021-8979    

DOI:10.1063/1.348387

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The breakdown voltage (VKB) of a cold cathode glass discharge tube, driven by negative voltage pulses, is greatly increased by charges which the pulses deposit on the inside walls of the tube. It is shown thatVKBcan be almost halved by neutralizing these negative wall charges with positive pulses of amplitudeV+, applied to the tube electrodes. Explanations are given of the dependence ofVKBonV+and the implications for gas discharge display systems are also considered.

ISSN:0021-8979    

DOI:10.1063/1.348388

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

An attempt was made to clarify the ionization mechanism and to interpret the characteristics of the measured Hg+ion density in low‐pressure Ar‐Hg discharge for the mercury lamp using the measured Hg6p3P0,1,2population density, electron density, and electron temperature. The stepwise ionization caused by collisions between Hg metastable atoms and electrons and that between Hg excited atoms were concluded to be the most important ionization processes. As the extinction processes of Hg+ions, the ambipolar diffusion and recombination of Hg atoms, Hg+ions and electrons were taken into account. The measured dependencies of the Hg+ion density on bath temperature was interpreted well with the model including the above processes.

ISSN:0021-8979    

DOI:10.1063/1.348389

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The average electron densities in CH4/H2/Ar and CCl2F2/O2electron cyclotron resonance discharges typical of those used for etching InP, GaAs, and related materials have been measured approximately 4 cm downstream from the multipolar microwave source as a function of microwave power (50–300 W), additional radio‐frequency power (10–50 W), pressure (1–20 mTorr), flow rate (30–90 standard cubic centimeters per minute) and gas composition. At 1 mTorr pressure and 10 W rf, the electron densities (and semiconductor etch rates) increase rapidly with microwave power, from 1.3×1011cm−3for 5CH4/17H2/8Ar and 6×1010cm−3for 28CCl2F2/2O2discharges at 50‐W microwave power, to 9×1011cm−3and 3×1011cm−3, respectively at 300‐W microwave power. At the highest microwave power levels (≥200 W) the InP and GaAs etched surface morphologies are rough due to preferential removal of one of the lattice constituents from each material. The electron densities in both types of discharge show moderate increases with increasing rf power level, pressure or higher Ar or O concentrations.

ISSN:0021-8979    

DOI:10.1063/1.348390

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Three amorphous alloy powders in the Ti‐Fe system with the ratios of Ti:Fe at 1:2, 1:1, and 2:1 were prepared by mechanical alloying of the elemental powders in a high‐energy ball mill. The amorphous powders were characterized by x‐ray diffraction and high‐resolution transmission electron microscopy. A complete amorphization of Ti1Fe1was achieved, whereas a remaining crystalline portion besides the amorphous phase was present in Ti2Fe1and Ti1Fe2. The crystallization temperatures for these alloys detected by differential scanning calorimetry varied from 714 to 791 K, which were corresponding to half of their melting points.

ISSN:0021-8979    

DOI:10.1063/1.348391

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Single‐crystal germanium on (11¯02) sapphire films are grown after a substrate preanneal of 1400 °C and at growth temperatures above 700 °C. At a growth temperature of 800 °C, the nucleation site density was ∼1011cm−2. For thin germanium films, the isolated islands were singly oriented, with single‐crystal films obtained for thicker grown films. A 400 °C growth temperature on sapphire was insufficiently high to get epitaxial growth and produced polycrystallites. Growth at 400 °C on an 800 °C grown germanium template did result in epitaxy. However, a high fraction of the twinned orientation was produced, resulting in a bicrystalline film.

ISSN:0021-8979    

DOI:10.1063/1.348392

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Single‐ and multiple‐energy Fe, Cr, and V ions were implanted into InGaAs. Annealing of the implanted InGaAs samples caused a redistribution of the implanted atoms, as determined by secondary ion mass spectrometry. Coimplantation of Fe with P did not prevent this redistribution. A transport equation calculation of Fe‐implantation‐induced stoichiometric disturbances in InGaAs was done. The lattice quality of implanted InGaAs was investigated by photoreflectance measurements. Fe‐implanted InGaAs has a resistivity close to the intrinsic limit, whereas Cr‐ and V‐implanted InGaAs have a lower resistivity than the unimplanted material.

ISSN:0021-8979    

DOI:10.1063/1.348393

出版商:AIP    

年代:1991

数据来源: AIP