摘要:

The electron energy distribution function (EEDF) in an argon planar inductively coupled plasma was measured by the method of laser Thomson scattering. In a low‐pressure discharge, a clear departure from a Maxwellian distribution function was observed; an unambiguous measurement of a non‐Maxwellian distribution in a low‐density glow discharge. The non‐Maxwellian EEDF became Maxwellian in a higher pressure discharge. These observations were attributed to the lack of randomizing collisions in the low‐pressure discharge and the increase in the number of these collisions at higher pressure. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117188

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The time‐integrated x‐ray emission from a hot, dense iron plasma has been recorded. The iron plasma was created when a target with a 1000‐A˚‐thick iron layer buried beneath 1000 A˚ of plastic was irradiated by a 300 fs pulse of 249 nm laser light at an intensity of approximately 1017W cm−2. Two models have been used to construct a synthetic x‐ray spectrum. The first employs detailed, spectroscopically accurate atomic data and the second uses a local thermodynamic equilibrium opacity model. The detailed model shows fairly good agreement with experiment whereas the opacity model only shows agreement in the gross features. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117189

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The physical nature of the forces acting between a laterally vibrating probe in air near a solid surface has been investigated using a calibrated method for the experimental determination of dynamic force. The frequency response of the probe vibrating near its fundamental bending resonance was measured as a function of distance as the probe approached the surface. The experimental results were compared with a continuum‐mechanical model of bending waves in a rod; the nature of the forces was inferred by determining the effect of various boundary conditions on the standing‐wave motion of the probe. The results conclusively show that while in the initial stage of approach the force is dominated by fluid‐dynamic effects, in the final stage of approach an elastic force appears. The appearance of the elastic deformation is characterized by a shift in the resonant frequency of the vibrating probe. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117190

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The self‐aligned formation of CoSi2was achieved on the selective epitaxial growth (SEG) silicon layer on (001)Si inside 0.1–0.6 &mgr;m oxide openings prepared by electron beam lithography. The uniform, high quality SEG Si layer was grown by ultrahigh vacuum chemical vapor deposition at 560 °C with Si2H6. Self‐aligned CoSi2film without lateral growth of silicide was grown on the SEG Si layer by rapid thermal annealing at 700 °C in N2ambient. The successful integration of the self‐aligned CoSi2and SEG of Si processes promises to be a viable process technology for the future deep submicron devices. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117191

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We present direct measurements of interwell carrier transport in InGaAsP quantum well (QW) laser structures performed by time‐resolved photoluminescence. Conditions of originally empty and filled wells are explored. In both cases, the time for the hole transport across the structure is found to be of the order of tens of picoseconds. Comparison of experimental results and simulations allowed us to develop an adequate interwell carrier transport model that includes thermionic capture/emission over the QW interfaces and drift/diffusion in the barrier regions. We show that dynamic consideration of carrier densities and band bending for each QW are essential. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117192

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We have investigated the atomic‐scale structure and electronic properties of GaN/GaAs superlattices produced by nitridation of a molecular beam epitaxially grown GaAs surface. Using cross‐sectional scanning tunneling microscopy (STM) and spectroscopy, we show that the nitrided layers are laterally inhomogeneous, consisting of groups of atomic‐scale defects and larger clusters. Analysis of x‐ray diffraction data in terms of fractional area of clusters (determined by STM), reveals a cluster lattice constant similar to bulk GaN. In addition, tunneling spectroscopy on the defects indicates a conduction band state associated with an acceptor level of NAsin GaAs. Therefore, we identify the clusters and defects as nearly pure GaN and NAs, respectively. Together, the results reveal phase segregation in these arsenide/nitride structures, in agreement with the large miscibility gap predicted for GaAsN. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117193

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Direct nitrogen implant into Si substrate prior to gate oxidation has been proposed to grow multiple gate oxide thicknesses on a single wafer. In this letter, we have studied the reliability of gate oxide grown on nitrogen‐implanted Si substrate. The effects of implant doses, sacrificial oxide thicknesses, and gate oxide thicknesses on gate oxide reliability have been investigated. It was found that there is a tradeoff between oxide thickness control and gate oxide reliability. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117194

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Single CdTe/CdMgTe quantum well (QW) structures are investigated by stationary and time‐resolved photoluminescence in the presence of an applied magnetic field. We study the dependence of the electron and the holegfactors on the well width by combining Zeeman measurements and the recently developed spin quantum beats technique. The experimental results show that both the electron and the holegfactors have the same sign in wide QWs and increase with decreasing well width. The electron spin phase relaxation time is about 250 ps in our QW structures. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117195

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We demonstrate the validity of the dead space approximation for impact ionization in silicon. Monte Carlo simulations are used to obtain realistic ionization probabilities, and the corresponding avalanche gain in constant field structures is computed. We show that the hard‐threshold dead space model is in good agreement with a more refined model taking into account soft‐threshold effects, if an effective threshold energy of 3 eV is adopted for electrons. We also show that hole nonlocal effects do not significantly affect the result. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117196

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report a study on the N incorporation in GaP grown by gas‐source molecular beam epitaxy using a N radical beam source. Contrary to theoretical predictions under thermoequilibrium conditions, GaNP with N concentration as high as 16% has been obtained without showing any phase separation, but increasing the growth temperature will result in a decrease of N incorporation. These results indicate that using nonequilibrium growth techniques can achieve GaNP alloys with a N concentration far greater than the thermal equilibrium solubility limit. Optical absorption measurements reveal that although the band gap energy of GaNxP1−xdecreases with increasing N concentration, it is still positive forxup to 16%, indicating that the material is not a semimetal but a semiconductor, contrary to theoretical predictions based on the Van Vechten’s quantum dielectric model. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117197

出版商:AIP    

年代:1996

数据来源: AIP