摘要:

Steady‐state positive column calculations can sometimes be simplified by writing the electron diffusion rate in terms of an effective length, thereby replacing a Laplacian with an algebraic quantity. When the electron continuity equation is purely linear in electron density, the characteristic diffusion length is useful for this purpose, since it can be used to relate the electron diffusion loss rate to the dimensions of a plasma and to calculate the electron temperature or operating electric field. If additional, nonlinear processes are introduced, the characteristic diffusion length is no longer appropriate for representing the diffusion rate. This paper presents a simple yet exact definition of a generalized diffusion length for calculations of the spatially averaged electron density in plasmas with electron production and loss rates linear and quadratic in electron density. This generalized effective diffusion length properly accounts for the average effect of electron diffusion for all possible signs and relative magnitudes of the linear and quadratic rates. Some properties of the effective diffusion length differ significantly from those of the characteristic diffusion length, which represents a special limiting case. Problems with other definitions of an effective diffusion length are discussed.

ISSN:0021-8979    

DOI:10.1063/1.328612

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

We show how relatively simple diffraction theory can be applied to layered ultrathin coherent structures to yield diffraction patterns with main peaks and satellites. We also discuss how the introduction of lattice strain into the model affects the results, and how this modified model might be applied to a real system.

ISSN:0021-8979    

DOI:10.1063/1.328613

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Ingots of AlxGayIn1−x−ySb were grown using a directional freeze technique. Slices were cut from these ingots and their compositions determined by an x‐ray fluorescence method. X‐ray powder photographs were taken of the slices to check for single phase condition and hence lattice parameter values were determined. Optical energy‐gap values were also obtained from standard transmission measurements. Empirical equations were then derived to fit the lattice parameter and energy‐gap data as functions of composition.

ISSN:0021-8979    

DOI:10.1063/1.328614

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Structure of amorphous silicon (a‐Si) vacuum deposited on single‐crystal (100) silicon (c‐Si) with and without clean surfaces achieved by ion sputtering and annealing has been examined by using electron paramagnetic resonance (EPR) and transmission electron microscopy (TEM) as a function of annealing temperature. Annealing behavior of EPR signal can be explained well on the basis of TEM observation that there are void networks ina‐Si film deposited onc‐Si with native oxide but no such structure ina‐Si film onc‐Si with clean surface. Structure ofa‐Si, where solid phase epitaxial growth occurs at a high rate, is compared with that of ion bombardeda‐Si.

ISSN:0021-8979    

DOI:10.1063/1.328615

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Either magnesium or zinc ions have been implanted in (100)‐oriented, Fe‐doped, semi‐insulating indium phosphide at room temperature or at 250 °C. Channeling effect measurements have revealed that the surface layer is transformed to an amorphous state by room‐temperature implants with a dose of mid‐1014/cm2. The implantation‐induced amorphous layers disappear after 700‐°C annealing, but a highly disordered region still remains if these amorphous layers exceed 0.23 &mgr;m in thickness. Carrier concentration and mobility profiles for Mg‐ and Zn‐implanted samples have been measured by differential Hall‐measurements. A dead layer, where no free carrier is detected, is formed near the implanted surface. The formation of the dead layer could be explained by the existence of the highly disordered region remaining after anneal and/or by the compensation effect due ton‐type carriers introduced near the surface by room‐temperature implant. It has been also shown that neither the amorphous layer nor the highly disordered region is formed in the samples where implantation is carried out at 250 °C, resulting in the annihilation of the dead layer from the carrier concentration profile.

ISSN:0021-8979    

DOI:10.1063/1.328430

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Flash x‐ray measurements have been made on GaAs metal semiconductor field effect transistor structures fabricated in both Cr‐doped and undoped semi‐insulating substrate material in order to characterize the levels responsible for long term transients in these devices. Prominent electron and hole traps with activation energies in the 0.76–0.90‐eV range have been identified. The main electron trap, which is present in both Cr‐doped and undoped substrates, appears to be primarily responsible for the observed transient response. However, traps related to Cr‐doping also contribute to the transient behavior.

ISSN:0021-8979    

DOI:10.1063/1.328431

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Room‐temperature photoluminescence measurements were made on 300‐keV proton‐bombarded GaAs as a function of dose, post‐bombardment time, and temperature of anneal and were compared with measurements on unbombarded surfaces annealed under identical conditions. For heavy‐dose (1017protons cm−2) samples the photoluminescence signal recovers exponentially with temperature of anneal, with an apparent activation energy of 1.15 eV. For lower‐dose samples deterioration or saturation of the recovery process occurs at an anneal temperature of approximately 800 °C. This is explained in terms of the formation of As vacancies near the surface during annealing.

ISSN:0021-8979    

DOI:10.1063/1.328432

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Silicide formation is strongly affected by the presence of oxygen contained in the metal film. A study has been performed by heating at various times and temperatures samples constituted by a thin Pt film sputter deposited on a silicon substrate. Four different oxygen concentrations were implanted in the Pt film ranging from 1 to 0.1 at.%. The presence of oxygen slows down the growth rate of Pt2Si. At 315 °C in the sample with an oxygen concentration of 1 at.%, about 1000 A˚ of Pt2Si are formed after 20 min of annealing. During the silicide formation, the oxygen originally contained in the platinum films segregates at the Pt2Si/Pt interface. This accumulation acts as a barrier for the transport of Pt and a new phase, PtSi, can form at the Pt2Si/Si interface. The dose necessary to stop the Pt2Si reaction is about (2–4)×1015at./cm2at 315 °C.

ISSN:0021-8979    

DOI:10.1063/1.328655

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Schottky barrier diodes of yttrium and yttrium silicide were fabricated onp‐type (111) silicon. The barrier heights of the diodes determined byI‐Vmeasurements were correlated with heat treatments and interface conditions as determined by Auger composition depth profiles. The as‐deposited Y‐Si contact had a barrier height of 0.70 eV. During heat treatment at 300 °C, oxygen diffused into yttrium and formed Y2O3, resulting in a barrier height of 0.65 eV. Yttrium silicide was formed at 410 °C that lead to a Schottky barrier height of 0.60 eV.

ISSN:0021-8979    

DOI:10.1063/1.328656

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The deposition mechanism for chemical vapor deposition glassy SiO2films using SiH4, O2, and N2mixtures has been studied. With an increasingPO2, the deposition rate increases in the lowerPO2region, while it decreases in the higherPO2region. The results were analyzed on the basis of the Langmuir‐Hinshelwood surface reaction mechanism. A rate equation was derived. It was found that two molecules of adsorbed SiH4and one atom of dissociatively adsorbed O2react on the surface. In the increasing region, the rate constant for surface reaction and adsorption coefficients for SiH4and O2were obtained by optimizing the parameters in the rate equation. The activation energy of the surface reaction and the heat of adsorption for SiH4and O2were obtained as 10±2, 7±1, and 9.5±2 kcal/mol, respectively. In the decreasing region, adsorption coefficients changed away from those in the increasing region, resulting in an abrupt decrease in deposition rate withPO2.

ISSN:0021-8979    

DOI:10.1063/1.328657

出版商:AIP    

年代:1981

数据来源: AIP