摘要:

The electrostatic potential profile in the accelerating gap in a plasma‐prefilled magnetically insulated intense pulsed ion beam diode has been determined using laser‐induced fluorescence spectroscopy. Results for a 300–400 kV planar diode are presented, both with and without an electron emitting vane protruding from the cathode. In both cases, a 5–6 mm accelerating gap forms in the 1012–1013/cm3plasma in a few nanoseconds. The experimental potential profiles are not consistent with electrons confined to a sheath near the cathode. Rather, electrons are required throughout the gap to explain the observations.

ISSN:0003-6951    

DOI:10.1063/1.102219

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Ionization onset in the ablation plume from KrF laser‐irradiated Cu targets in vacuum leads to a fast‐rising voltage transient on the target. This, together with ion probe measurements, provides information on the plasma parameters. With 30 ns pulses, plasma initiates at ∼108W cm−2; electron temperatures of 7 eV and ion energies of several hundred volts are produced at 2.2×108W cm−2.

ISSN:0003-6951    

DOI:10.1063/1.102220

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Near‐surface (∼1000 A˚) modification in the net carrier concentration inn‐type InP (n=6×1015–1.5×1017cm−3) was observed after reactive ion etching (RIE) in Cl‐based (CCl2F2/O2) or organic‐based (C2H6/H2) discharges. The carrier loss is slightly more pronounced in the latter case, due possibly to the creation of deep level, compensating acceptors at greater depths as a result of implantation of the light hydrogen ions. Near‐complete recovery of the initial carrier density occurs after annealing at 500 °C for 30 s. Structural disorder is detected by ion channeling to depths of ∼400 A˚ after C2H6/H2RIE with a self‐bias of 380 V. This disorder shows significant recovery after 400 °C, 30 s annealing. Current‐voltage measurements on Au Schottky diodes showed ohmic behavior after etching of the InP in a C2H6/H2discharge, due to the nonstoichiometric surface remaining after RIE. Diodes fabricated on CCl2F2/O2etched material show only a slight increase in reverse current compared to unetched control samples.

ISSN:0003-6951    

DOI:10.1063/1.102221

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A new selective epitaxial growth method of silicon on sapphire by disilane gas‐source molecular beam epitaxy (MBE) is proposed. Selective epitaxial growth of Si films on sapphire was achieved by irradiation of an electron beam on the sapphire surface before Si MBE. Si was not deposited on the sapphire surface irradiated by an electron beam, and was grown epitaxially only on the nonirradiated area. The selective epitaxial growth was confirmed by optical micrographs,insitureflection high‐energy electron diffraction, and Auger electron spectroscopy. It was recognized by x‐ray photoelectron spectroscopy that the sapphire surface was changed before and after electron beam irradiation: oxygen atoms on the sapphire surface were decreased due to irradiation of the electron beam and aluminum atoms mainly existed on the surface. This phenomenon can be considered to be the main cause of the selective epitaxial growth.

ISSN:0003-6951    

DOI:10.1063/1.102222

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

In this letter we report on improved phosphorus incorporation in amorphous SiC films as measured by the dc conductivity and activation energy. In this process, we show that preheating of the gas mixture is an important process parameter which leads to improved impurity incorporation.

ISSN:0003-6951    

DOI:10.1063/1.102223

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The passivating effects of plasma polymerized thin films of thiophene on the intrinsic properties of the surface ofn‐GaAs (100) have been studied by means of Raman scattering, photoluminescence, and capacitance‐voltage measurements. After passivation, the low‐temperature photoluminescence efficiency ofn‐GaAs is increased three times and the surface barrier at the interface between polymer and GaAs is reduced. The surface electric field and barrier height determined by Raman scattering studies and also from capacitance‐voltage measurements are shown to be lowered implying that the band bending is controlled externally.

ISSN:0003-6951    

DOI:10.1063/1.102224

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Photochemical vapor deposition of carbon films fromn‐butane gas has been successfully done, for the first time, at room temperature using synchrotron radiation as a light source. The deposited films are hydrogenated amorphous carbon films withsp3bonds. The deposition rate increases with negative bias.

ISSN:0003-6951    

DOI:10.1063/1.102225

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A new technique for determining carrier diffusion lengths by cathodoluminescence measurements is presented. The technique is extremely accurate and can be applied to a variety of structures. Ambipolar diffusion lengths are determined for GaAs quantum well material, bulk GaAs, Al0.21Ga0.79As, and Al0.37Ga0.63As. A large increase in the diffusion length is found for Al0.37Ga0.63As and is attributed to an order of magnitude increase in lifetime.

ISSN:0003-6951    

DOI:10.1063/1.102226

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We demonstrate for the first time that ion implantation and implant activation annealing, combined with a heavily doped InGaAs surface layer, can be used to make nonalloying shallow ohmic contact to ann‐type InGaAs (or GaAs) quantum well. Quantum Hall effect and Shubnikov–de Haas oscillations are clearly observed, which indicates that electrons in the quantum well remain two dimensional despite the post‐implantation high‐temperature annealing. This technique can be applied to devices that would need to make shallow ohmic contact to a thin (∼100 A˚ or less) quantum well, where existing selective etching approaches fail to work.

ISSN:0003-6951    

DOI:10.1063/1.102227

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

It has been shown by several workers that the passivation of GaAs surfaces using sulfides results in a large reduction in the surface recombination velocity accompanied by an increase in the band bending onn‐type samples. This apparently contradictory pair of results leads to the suggestion that the responsible electronic states are a midgap donor compensated by an acceptor near the valence‐band maximum. We explore the consequences of such a model, particularly when the midgap state is assumed to be a double donor. In the double donor case, simple qualitative arguments indicate that the surface recombination velocity can be reduced by a factor much greater than the reduction in surface‐state density. The model is consistent with observations made using a variety of experimental techniques. A correlation between the electronic states and surface chemistry is made, and the As and Ga antisite defects are discussed as candidates for the donor and acceptor states.

ISSN:0003-6951    

DOI:10.1063/1.102228

出版商:AIP    

年代:1989

数据来源: AIP