摘要:

We calculate the time‐dependent electrical conductivity &sgr;(t) for the nonequilibrium carriers excited by a subpicosecond laser pulse in a polar semiconductor like GaAs. The photoexcited carriers are assumed to relax towards equilibrium by emitting longitudinal optical (LO) phonons in a cascade via the strong Fro¨hlich interaction. We show that &sgr;(t), obtained in the picosecond time domain, has a highly nonlinear time evolution. It develops a pronounced dip, with its value becoming negative, whenever the generated low density carrier distribution is sharply peaked initially at energy &egr;&bartil;mℏ&ohgr;LO,m=integer, ℏ&ohgr;LObeing the long wavelength LO phonon energy.

ISSN:0003-6951    

DOI:10.1063/1.98990

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Ohmic contacts ton‐GaAs (Si doped at 2×1018cm−3) with contact resistances of 0.7–1.5×10−6&OHgr; cm2have been formed with deposited layers of In and Pd. The layers were sequentially evaporated and then annealed at 500 °C for 20 s to form In3Pd and a top layer of In. In addition a thin (≊200 A˚) reacted layer was formed at the GaAs interface. Uniform interface morphology was observed with no evidence of localized reaction.

ISSN:0003-6951    

DOI:10.1063/1.98429

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Sinusoidal intensity modulation in the frequency range 1 Hz–65 kHz has been used to study the frequency dependence of the photocurrent at thep‐GaP/0.5 M H2SO4junction. It is shown that the high‐frequency response is independent of surface recombination, so that the diffusion length of electrons and the absorption coefficient of the semiconductor can be derived. In the case ofp‐GaP, the electron diffusion length was found to be (7.9±0.8)×10−6cm, and the absorption coefficient at 442 nm was calculated to be (3.2±0.3)×104cm−1.

ISSN:0003-6951    

DOI:10.1063/1.98430

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A dependence of boron anomalous diffusion on defect depth position has been observed after furnace and electron beam annealing of samples damaged with28Si ions implanted at different energies. This behavior was correlated with the vacancy and interstitial excesses, produced under bombardment in the surface region and in depth, respectively. The spatial separation of these point defects was evidenced by the analysis of the intensity profiles obtained by double‐crystal x‐ray diffraction.

ISSN:0003-6951    

DOI:10.1063/1.98431

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The effective dopant concentration determined from the capacitance minimum in the high‐frequency capacitance‐voltage curve is related to the actual majority‐carrier density profile through a simple integration formula. Based on this relationship, the nonuniform substrate doping effect on the analysis of group‐III acceptor hydrogenation experiments in silicon is examined. It is found that the procedure in determining the kinetic coefficients by fitting the effective dopant concentration versus avalanche injection or annealing time curves is appropriate if the hydrogen concentration is assumed uniform throughout the semiconductor surface space‐charge layer.

ISSN:0003-6951    

DOI:10.1063/1.98432

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Silicon monoxide and silicon dioxide form insulating films that are commonly used in microelectronic devices. In the technology of devices containing silicon, the insulating silicon dioxide films are formed on the silicon wafers using conventional methods of thermal oxidation. This technique, which requires long periods of annealing (30–60 min) and high temperature (&bartil;1000 °C), is known to induce different types of physical degradation in the device. In this letter, we demonstrate the possibility of converting silicon monoxide deposited at room temperature to silicon dioxide by rapid thermal annealing. Although the annealing temperature is high (700–1100 °C) the time is very short (within seconds), so that this process may still be compatible with the requirements of low‐temperature processing.

ISSN:0003-6951    

DOI:10.1063/1.98433

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Supercomputer simulations of molecular beam epitaxial growth are applied to modeling processing profiles. Illustration is provided by investigating the relative advantages of high incident beam flux growth, interrupted periodically to allow the growth front to relax, versus continual growth at a relatively low deposition rate.

ISSN:0003-6951    

DOI:10.1063/1.98434

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

High‐temperature oxygen ion implantation has been used to form buried oxide layers in silicon single crystals. The ion implantation and substrate variables, particularly the substrate temperature, were optimized to obtain silicon layers with controlled microstructures near the surface. The as‐implanted specimens were subsequently annealed at high temperatures to form a buried SiO2layer with sharp interfaces and to minimize dislocation densities in the top silicon layers. The specimens were characterized by cross‐section transmission electron microscopy and these results were compared with those obtained using spectroscopic ellipsometry. We discuss the application of the nondestructive scanning ellipsometry technique in the characterization of silicon‐on‐insulator materials.

ISSN:0003-6951    

DOI:10.1063/1.98435

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Core level photoemission spectroscopy using synchrotron radiation was performed to study the activity of sodium on the nitridation of the (100) face of silicon. At room temperature, the exposition to molecular nitrogen of a Si (100) surface modified by a sodium monolayer induced the formation of a SiNxcompound. The sodium catalyst is removed from the surface by thermal desorption at moderate temperature. Subsequently, a clean (sodium free) Si3N4‐Si interface was formed at a much lower temperature than without the alkali metal.

ISSN:0003-6951    

DOI:10.1063/1.98436

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Deep centers induced by hydrostatic pressure in GaAs:Si have been studied by deep level transient spectroscopy and constant temperature capacitance transient techniques. The capture behavior of these centers has been studied in detail and found to be consistent with the multiphonon emission theory. The pressure coefficients of the ionization energy and the barrier height are consistent with the large lattice relaxation model proposed by D. V. Lang and R. A. Logan [Phys. Rev. Lett.39, 635 (1977)].

ISSN:0003-6951    

DOI:10.1063/1.98437

出版商:AIP    

年代:1987

数据来源: AIP