摘要:

We have recorded, in the energy range of ∼4–11 eV, radiation from electron cyclotron resonance microwave plasmas generated when coupling microwave energy in a number of gases and gas mixtures appropriate for plasma deposition or etching. Molecular, atomic, and ionic emissions are observed in this range attesting to the major collisional processes (dissociation, excitation, and ionization) with hot electrons. The neutral atom temperature has been measured by standard spectroscopic techniques and found to be in the range of 0.1–0.3 eV, much lower than the electron temperature of the same plasmas. The main discharge parameters (i.e., gas pressure, flow rate, microwave power) have been varied to interpret their influence on the plasma radiation in terms of plasma parameters.

ISSN:0021-8979    

DOI:10.1063/1.360525

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A model is developed for a direct‐current glow discharge in argon by a combination of a hybrid Monte Carlo fluid model of electrons and ions in the entire discharge and a Monte Carlo model of ions and fast atoms in the cathode dark space, in which fast ion and atom impact ionization are incorporated. The relative importance of these processes, compared to electron impact ionization is investigated, as a function of distance from the cathode and at different discharge conditions. It is found that they are dominant close to the cathode, and that they gain importance with increasing voltages. With the incorporation of these processes it was possible to predict current–voltage relations which are in excellent agreement with experiment. Also, the length of the cathode dark space, as a function of pressure and voltage, is calculated; the results agree with Aston’s empirical formula. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360526

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We present a model to study high density plasma reactors used in semiconductor processing. The model is based on a continuum approach with conservation equations for mass, momentum, and energy in a multicomponent, multitemperature system. The governing equations are radially averaged to obtain a one‐dimensional model for the transport of neutrals and charged species in the flow direction. Processes at the radial wall are properly included as source/sink terms by weighting with surface area to volume ratio. The model is applied to an electron cyclotron resonance reactor and simulations of an argon discharge are presented for pressures in the range of 1–10 mTorr and flow rates of 5–80 sccm. The predictions of plasma density, electron and gas temperatures, pressure, and neutral density are consistent with experimental observations and compare favorably with data. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360776

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The characteristics of a 13.56 MHz capacitively coupled rf glow‐discharge Ar plasma are studied by particle‐in‐cell simulation. The model simulates a planar plasma device which can be approximated using a one‐dimensional plasma model. The model has proven to be useful to investigate the effect of varying control parameters such as neutral gas pressure, driver frequency, applied rf voltage on the characteristics of the discharge. A set of equations describing the dynamics of the system are presented and used to give analytic scaling laws. The simulation code is used to calculate the pressure dependence of plasma density, sheath width, peak position of the ionization event, and absorbed rf power. Scaling laws relating the control parameters to other operating functions such as average plasma potential, central electron density, absorbed rf power are examined and these functions are compared with simple analytical scaling formula. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360527

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We present a simple model for the keyhole plasma in deep penetration welding with a laser beam. Simplifying the complete set of transport equations investigated by C. Tix and G. Simon [Phys. Rev. E50, 453 (1994)] for high laser powers yields an energy balance for the plasma, which can be treated analytically. The mean plasma temperature is calculated accounting for higher charge states of the ions. For high laser intensities double and higher charged ions dominate in the plasma bulk in the case of iron. The degree of absorption remains approximately constant for increasing laser power. The critical Pe´cle´t number for which the absorbed laser energy is able to maintain a keyhole increases strongly with increasing laser power. The energy absorption by the plasma is enhanced for higher modes of the laser intensity distribution. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360528

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The strain relaxation of In0.1Ga0.9As layers on GaAs (110) was studied by transmission electron microscopy (TEM) and x‐ray diffraction. TEM observation showed that strain relief in the (110) interface is initially dominated in the [001] direction by the formation of 60° type dislocations and stacking faults via {111}⟨011⟩ slip systems for layer thicknesses up to approximately 200 nm. As the layer thickness increases, {113}⟨011⟩ slip systems became active and the resultant misfit dislocations contribute strain relief in both [001] and [11¯0] directions. The efficiency of strain relief by the different misfit dislocations is discussed. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360529

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The characteristics and annealing behavior of vacancy clusters in neutron transmutation doped silicon (NTDSi) were investigated by means of Fourier transform infrared spectroscopy (FTIR) and photoinduced transient spectroscopy. FTIR results showed that three IR absorption peaks at 707, 742, and 776 cm−1occurred during annealing NTDSi samples at temperatures ranging from 350 to 600 °C. By comparing the present results with those reported earlier, the defect center (we named it theP0center) which gives rise to these IR absorption bands, was assumed to be a multivacancy cluster consisting of at least six vacancies. Photoinduced transient spectroscopy results showed that aP0center introduced two acceptor levels atEc−0.427 eV andEc−0.524 eV inside the energy gap. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360530

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We grow InAs layers on (001) on‐axis and misoriented GaAs substrates by molecular beam epitaxy, respectively. The critical thickness of each InAs layer is investigated with photoluminescence spectroscopy and transmission electron microscopy (TEM). We show that the critical thickness is significantly influenced by the substrate misorientation. The critical thickness of the InAs layer grown on the GaAs substrate misoriented toward the [11¯0] direction becomes thicker [5 monolayers (ML)] than that (3 ML) of the InAs layers grown on the GaAs substrates (001) on‐axis or misoriented toward the [110] direction. The plan‐view TEM images show that the islands grown coherently do not coalesce even beyond the on‐axis critical thickness (3 ML). The strain energy is calculated based on valence‐force‐field model to investigate the interaction between dislocation and step in case on misoriented substrate. As results, we show that dislocation has the minimum length above which dislocation can stably exist and that the extra strain energy generated at the cross point of dislocation and step plays an important role in dislocation generation. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360531

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

This paper describes a model that simulates the precipitation kinetics of oxygen and the evolution of the precipitate density in annealed Czochralski‐silicon wafers. A discrete rate equation representation combined with Fokker‐Planck equations are used to treat precipitation of oxygen and simultaneous formation of bulk stacking faults. This approach allows one to describe both statistical clustering during nucleation and diffusional transport during growth. The model considers explicitly influences of self interstitials and stress on precipitation of oxygen and thus is able to accurately predict the experimental observations published previously. In particular, we compare simulation results of precipitated oxygen concentration in 2‐step, 3‐step, complementary metal oxide semiconductor type multi‐step, and rapid thermal anneals with experimental results taken from the literature and discuss them. ©1995 American Institute of Physics. 

ISSN:0021-8979    

DOI:10.1063/1.360532

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Two infrared laser beams coupled into the tunneling junction of a scanning tunneling microscope lead to the generation of a signal at the difference frequency. In this article it is described that two different frequency mixing mechanisms are responsible for this process. One part of the signal is generated through a mixing process owing to the nonlinearity in the static current‐voltage characteristic. Another part has its origin in a nonlinear susceptibility at the surface; it therefore corresponds to frequency mixing in nonlinear optics. It will be shown that the difference‐frequency signals generated by the two processes can be separated owing to their different dependence on the tip‐sample distance. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360533

出版商:AIP    

年代:1995

数据来源: AIP