摘要:

The momentum, energy, and velocity characteristics of plasma ablating from planar targets irradiated by long Nd‐laser pulses (4 ns,<1014W/cm2) are measured and the dependence of ablation parameters upon absorbed irradiance is determined. Large laser spots are used in these experiments so that the results are not sensitive to boundary effects.

ISSN:0003-6951    

DOI:10.1063/1.92788

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A sensitive submillimeter heterodyne receiver has been used to measure electron cyclotron emission at the 2nd through the 5th harmonics from thermal plasmas in Alcator A. A sensitive diagnostic of the electron energy distribution function is obtained from intensity ratios of the optically thin harmonics, in particular the small runaway fraction (∼10−6) that exists even in well thermalized Alcator A plasmas. Also the 4th and 5th harmonics are a sensitive measure of impending plasma disruption due to vessel air leaks.

ISSN:0003-6951    

DOI:10.1063/1.92789

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Raman spectra of thin film GexSe1−x(x= 0.1, 0.33) glasses shows them to be structurally and compositionally similar on a molecular scale whether prepared by evaporation or sputtering techniques. Their sensitivity as silver‐doped photoresist materials correlates directly with information obtained from backscattering Raman experiments on the initially prepared films. Low sensitivity in some films prepared by sputtering onto low‐temperature substrates is attributed to film contamination, probably by oxygen containing impurities or by other materials that inhibit formation of optically absorbing Ge–Se bonding networks.

ISSN:0003-6951    

DOI:10.1063/1.92790

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

An explanation is given for the strong dependence of electrical conductivity of semi‐insulating polycrystalline silicon films on oxygen content. The proposed model assumes a shell structure such that each Si grain is surrounded by a layer of SiO2, the thickness of which is related to the oxygen content of the film. The conduction proceeds by tunneling of thermally generated carriers through the oxide layers separating adjacent grains. The model properly predicts the dependence of the low‐field conductivity on both oxygen concentration and temperature without any adjustable parameters. Evidence for oxide barrier lowering for barrier thicknesses <5 A˚ is observed.

ISSN:0003-6951    

DOI:10.1063/1.92791

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Reliability of pulsed electron‐beam‐alloyed AuGe/Pt ohmic contacts on GaAs has been studied and compared with thermally alloyed contacts. Electron‐beam‐alloyed contacts have excellent surface morphology and low contact resistance, but are not as reliable as thermally alloyed contacts; the specific contact resistance deteriorates with thermal aging at 250 °C. The degradation is explained by the interdiffusion and compound formation in the metals during aging.

ISSN:0003-6951    

DOI:10.1063/1.92792

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

A two‐beam photoacoustic technique is employed to monitor ultraviolet light‐induced darkening of ZnS (Mn, Cu) powder used for large‐area electroluminescent panels. The darkening process occurs for ultraviolet irradiation at wavelengths less than 345 nm. Photoacoustic measurements are made of the light‐induced change in the absorption spectrum and the influence of doping and contamination by atmospheric water on darkening rates.

ISSN:0003-6951    

DOI:10.1063/1.92793

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Continuous single‐crystal Si sheets over SiO2with areas of several square centimeters have been produced from poly‐Si films by the LESS technique (lateral epitaxy by seeded solidification). Seeding is achieved either with a narrow stripe opening in a recessed SiO2layer on a single‐crystal Si substrate or with an external single‐crystal Si seed.N‐channel metal‐oxide‐semiconductor field‐effect transistors (MOSFET’s) fabricated in these films exhibit surface electron mobilities as high as 700 cm2/V s.

ISSN:0003-6951    

DOI:10.1063/1.92794

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The redistribution of recoil oxygen implants produced by the implantation of As ions through oxide layers on Si substrates has been investigated at annealing temperatures in the range 4000–1000 °C. Using transmission electron microscopy and secondary ion mass spectrometry profiling, it has been shown that the implanted (recoil) oxygen is rapidly gettered into residual damage structure at anneal temperatures < 900 °C. At temperatures ⩾ 1000 °C residual damage gettering sites are annihilated, releasing oxygen to migrate toward the Si surface. At the higher‐annealing temperatures, oxygen has been shown to outdiffuse rapidly into the overlying (1000 A˚) oxide layer on the sample surface.

ISSN:0003-6951    

DOI:10.1063/1.92795

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The noise performance of ’’T’’ shaped Ti/W/Au gate GaAs Schottky‐barrier field‐effect transistors (FET’s) fabricated on channel layers grown by molecular beam epitaxy (MBE) is reported. The nominal gate length was about 0.7 &mgr;m with a total gate width of 250 &mgr;m. Typical noise figures and the associated gains at room temperature were 1.2 and 14 dB at 4 GHz, and 1.9 and 8.5 dB at 12 GHz. To our knowledge, these are the best results reported to date by MBE. These preliminary results, while not reaching the state of the art, do show the promise of MBE for high‐quality GaAs FET’s.

ISSN:0003-6951    

DOI:10.1063/1.92796

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Steady‐state velocity field characteristics for photoexcitedminorityelectrons inp‐In0.53Ga0.47As are reported. A low‐field drift mobility of 6000 cm2/V s for ∼1017cm−3impurities and a high‐field drift velocity of 2.6×107cm/s at 7.5 kv/cm are found. There is no evidence of transferred electron effects, a result which we attribute to energy scattering by holes and which leads to an enhancement of electron drift velocity.

ISSN:0003-6951    

DOI:10.1063/1.92797

出版商:AIP    

年代:1981

数据来源: AIP