摘要:

Tunable infrared diode laser spectroscopy has been applied to the study of CH4plasmas generated in a deposition reactor run at 20 kHz. Absolute number densities of CH4, C2H4, and CH3have been measured as functions of pressure and current. A qualitative explanation of the results is presented.

ISSN:0003-6951    

DOI:10.1063/1.103727

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

It is shown that in the vicinity of 77 K beryllium has a superior specific conductance compared with the nominally excellent metallic conductors aluminum and copper. It is concluded that beryllium should be considered for some conduction applications, despite its well known toxicity problems.

ISSN:0003-6951    

DOI:10.1063/1.103702

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Lattice strain in self‐ion‐implanted Si is investigated. Under certain irradiation conditions, a unique strain field is shown to form over the range of the ions. This strain field is one‐dimensional and expands the lattice along the direction normal to the surface of the crystal. This phenomena is investigated over a wide range of ion energy (100 keV and 1.25 MeV) and at different implantation temperatures. The presence of uniaxial strain is shown to correlate with a particular damage morphology in Si. This ion‐induced morphology and the irradiation conditions under which it forms are discussed, as well as the mechanism which leads to uniaxial, lattice strain. Both ion channeling and x‐ray diffraction analyses are used to characterize the strain field.

ISSN:0003-6951    

DOI:10.1063/1.103703

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The phenomenon termed fractoemission was monitored in soda‐lime‐silica glass specimens during slow crack growth. No electron, ion, or photon signals were detected until crack velocities reached approximately 10−2m/s. These observations suggest that the more intense fractoemissions observed during fast fracture are due to dissipation of the excess energy associated with unstable crack growth, but more significantly that fractoemissions are not fundamental to crack propagation in glass.

ISSN:0003-6951    

DOI:10.1063/1.103704

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We measured impact ionization rates in AlxGa1−xSb atx=0.06, where the band‐gap energyEgequals the spin‐orbital splitting energy &Dgr;, in an electric field of 1.5×105–3.2×105V/cm. By considering exact field profile in the depletion layer for each sample, the ionization rates of AlxGa1−xSb have been determined to be &agr;=2.35×106 exp(−1.30×106/E) and &bgr;=9.02×105 exp(−9.03×105/E). Although our data have not shown the resonant enhancement of hole ionization rates described by O. Hildebrand, W. Kuebart, and M. Pilkuhn [Appl. Phys. Lett.37, 801 (1980)], exact values of impact ionization rates have been established in practical electric fields required for designing AlxGa1−xSb avalanche photodiodes.

ISSN:0003-6951    

DOI:10.1063/1.103705

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

n‐type doping of mercury cadmium telluride was achieved using trimethylindium as the dopant source. The layers, grown by the alloy growth technique, were doped to ∼5×1018cm−3. The donor concentration in these layers was found to exhibit a linear dependence on the dopant partial pressure over the carrier concentration range from 5×1016to 3×1018cm−3. Reasonably high electron mobility values were observed in these indium‐doped layers. Typically, layers with a Cd fractionx=0.23, doped to 3.5×1016cm−3, exhibited a mobility value of 7.5×104cm2/V s at 40 K. High electron mobility values, measured over the entire doping regime, suggest a high electrical activity of indium in these layers. The optically measured band edge in these indium‐doped layers was observed to shift to higher energy with increasing doping. The band‐edge energy values measured in 1×1017and 3×1018cm−3doped layers correspond tox=0.23 andx=0.3, respectively. This increase can be due to an increase in the Cd fraction, or to a Burstein–Moss shift of the band edge with doping.

ISSN:0003-6951    

DOI:10.1063/1.103706

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A recent review suggests that the commonly cited value of 1.45×1010cm−3for the silicon intrinsic carrier concentration at 300 K is inconsistent with the best experimental and theoretical results. An alternative value of 1.08×1010cm−3was suggested. A new experimental measurement of 1.01×1010cm−3is reported with an estimated one standard deviation uncertainty of only 3%. This appears to be the most accurate experimental determination of this parameter at any temperature.

ISSN:0003-6951    

DOI:10.1063/1.103707

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

High quality SiO2films were deposited by plasma‐enhanced chemical vapor deposition on GaAs wafers which received different surface treatments. It was found that metal‐oxide‐semiconductor (MOS) capacitors which received surface nitridation were unstable under high‐temperature anneal (600 °C). These instabilities are interpreted in terms of free As precipitates at the interface. When, instead, a thin Si layer was deposited on the GaAs surface, stable interfaces were obtained at 600 °C. These MOS capacitors appear to show both deep depletion and inversion.

ISSN:0003-6951    

DOI:10.1063/1.104217

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We have studied the one‐dimensional (1D) subband energies in quantum wires fabricated on GaAs‐GaAlAs heterostructures. Magnetoresistance oscillations were used to investigate the influence of an applied gate voltage on the 1D subband energies for various geometrical widths of the fabricated quantum wires. For the first time, we measure directly the 1D subband energies by tunneling spectroscopy. As a result, both the confining potential and the influence of an additional magnetic field are well described by a simple harmonic oscillator model.

ISSN:0003-6951    

DOI:10.1063/1.103708

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The tunneling dynamics of photogenerated holes in a biased GaAs/AlGaAs double‐barrier resonant tunneling structure is studied using time‐resolved photoluminescence. For voltages biasing the structure in the resonant tunneling regime, a single exponential time decay was observed. However, for voltages which bias the structure in the nonresonant tunneling regime, beyond the region of negative differential resistance, the exciton decays with two time constants: one similar to that observed at low voltages and one that is approximately one order of magnitude slower. We attribute the fast time constant to the decay of exciton population originating from holes photoexcited directly in the well. The slower time constant is associated with excitons that are created from holes which are photoexcited in the GaAs contact region, and which subsequently tunnel into the well.

ISSN:0003-6951    

DOI:10.1063/1.103709

出版商:AIP    

年代:1990

数据来源: AIP