摘要:

Oxygen concentration of silicon has been determined by the ratio of theAcenter toEcenter in gamma‐irradiatedn‐type silicon. The concentrations of these defects were measured by the deep‐level transient spectroscopy technique. It has been found that the ratio of theAcenter toEcenter is simply proportional to that of oxygen to phosphorus content by a factor of 0.072. In addition to extending the range of sensitivity to oxygen to levels below that obtainable using infrared absorption, this new method permits easy determination of the distribution of oxygen.

ISSN:0021-8979    

DOI:10.1063/1.345619

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The concept of a macrokinetic distribution (MKD) is used to develop a theory of nonequilibrium carrier transport in multivalley semiconductors. The MKD is a momentum‐dependent function with macroscopic space‐time scales, whose equation of evolution is macroscopically equivalent to the semiclassical Boltzmann transport equation for the phase‐space distribution. A MKD is obtained for each valley and used to close the set of coupled moment equations that describe carrier transport in each valley. The resulting set of equations constitutes the model. A two‐valley model is developed to illustrate the theoretical procedure. Results are obtained for the response of electrons to a rapidly varying (in time) electric field. These results are compared to those obtained using Monte Carlo (MC) methods and also an equivalent single‐valley model. Excellent agreement is obtained between the macrokinetic model and the MC results. The single‐valley model is shown to be inadequate in situations where intervalley carrier transfer is significant.

ISSN:0021-8979    

DOI:10.1063/1.345620

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

This work reports on the result of electrical conductivity measurements carried out on coconut‐shell activated carbon. The results suggest that the charge carriers moved by variable‐range hopping below 200 K, by hopping among localized energy states between 200 K and 385 K, and by percolation through energy states close to the mobility edge above 385 K. In the latter two conduction processes, significant additional frequency‐dependent contributions to the conductivity were observed and are tentatively attributed to polarization of unremovable lignin and/or ionic impurities. These explanations are based on the present trends of the electrical transport theory for amorphous semiconductors.

ISSN:0021-8979    

DOI:10.1063/1.345621

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Time‐of‐flight (TOF) hole drift mobility (&mgr;d) measurements have been carried out on vacuum deposited and identically ageda‐Se photoreceptor type films over a temperature range encompassing the glass transformation region to study the nature of mobility controlling shallow traps in this elemental chalcogenide semiconductor. Differential scanning calorimetry (DSC) experiments using both heating and cooling scans have also been carried out on the same films to correlate the enthalpy relaxation phenomenon with the TOF drift mobility dependence on temperature. By considering the heating rate dependence of the minimum peak in the &mgr;dvsTbehavior and the heating and cooling rate dependence of the DSC glass transition temperature, it is shown that the mean retardation times, &tgr;&mgr;and &tgr;H, associated with the relaxation of the shallow traps and the enthalpy, respectively, have similar temperature dependencies, essentially Vogel–Tammann–Fulcher type, with negligible structural contribution. Correlation is also established with the relaxation of the mechanical properties ofa‐Se, viz., microhardness. Moreover, the rate of equilibration of shallow traps ina‐Se is found to be inversely proportional to the viscosity, &eegr;, i.e., (∂Nt/∂t)T∼1/&eegr;, or &tgr;&mgr;∼&eegr;. The present work provides further experimental evidence that the shallow traps ina‐Se are structural defects which are thermodynamic in origin and it also shows that their equilibration involves atomic motions similar to those which control the viscosity.

ISSN:0021-8979    

DOI:10.1063/1.345592

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A new expression of the transverse acoustoelectric voltage (TAV) is obtained for semiconductors including both majority and minority carriers. Numerical results are given and compared for LiNbO3/Si and LiNbO3/GaAs structures. It is shown that the influence of the minority carriers is restricted to quasi‐intrinsic semiconductors. The change in sign of the TAV for low conductivities and low frequencies, previously predicted for extrinsic semiconductors, is confirmed.

ISSN:0021-8979    

DOI:10.1063/1.345593

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The effect of the impact ionization dead space on avalanche multiplication and noise has been assessed for uniformp‐i‐navalanche photodiodes. This has required the development of a new numerical technique. The well‐established McIntyre theory of avalanche noise [IEEE Trans. Electron DevicesED‐13, 164 (1966)], which neglects the ionization dead‐space effect, has been shown to overestimate the excess noise factor. The implications of the dead‐space effect, for ionization coefficient determination and the interpretation of measured excess noise factors, are discussed.

ISSN:0021-8979    

DOI:10.1063/1.345596

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

An analysis of the reaction of Au and Au‐In alloys with InP has permitted the identification of the mechanisms occurring during the first two stages of the Au‐InP interaction. The first stage of the interaction, during which the Au is converted to a saturated Au(In) solution, is controlled by the vacancy‐generation rate at the free surface of the metallization. The activation energy for this process is the activation energy for Au self‐diffusion. Evidence is presented for the existence of large localized variations in this value due to surface related effects. At the completion of stage I stage II becomes active and continues until the metallization is converted to Au3In. This process, proceeding via an interstitial interchange mechanism, is many orders of magnitude slower than stage I. The rate‐limiting step, with an activation energy of 2.8 eV, is shown to be the diffusion of In from the InP‐metal interface. The P atoms that are released when In enters the metallization during stage I leave the system without reacting, whereas in stage II they form a compound (Au2P3) at the InP‐metal interface. The presence of the Au2P3severely retards the stage II interaction rate.

ISSN:0021-8979    

DOI:10.1063/1.345597

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The electrical properties of metal/implanted (amorphous) Si contacts were studied, emphasizing the effects of the doping level, of the metal type, and of the heat treatments applied prior to the metal deposition. The implantation was carried out using 60‐keV Ar+ions at a dose of 1016cm−2, and resulted in the formation of a thin (1000‐A˚‐thick) amorphous layer on top of the crystalline substrate. The doping level of the implanted Si affected the current‐voltage (I‐V) characteristics of the contacts mainly in the reverse bias (low doping–low currents), while the forward bias characteristics were quite independent of this parameter. The device characteristics were very sensitive to the metal type, Al, Ti‐W, or Pt. Thermal treatments applied prior to the metal deposition affected the characteristics by lowering the device resistance in correspondence with the thinning of the amorphous layer as a result of epitaxial regrowth. TheI‐Vcharacteristics, as well as their dependence on the different process parameters, are explained using a model of charge injection into a thin layer of trap rich amorphous Si bounded by a metal/a‐Si interface on one side and by ana‐Si/c‐Si heterojunction on the other side.

ISSN:0021-8979    

DOI:10.1063/1.345570

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Based on a nonlinear coupling between the etchant species and the photo‐induced carriers during photoelectrochemical etching of semiconductor surfaces, we propose that an optimum exists for the reaction rate as a function of electrolyte concentration.

ISSN:0021-8979    

DOI:10.1063/1.345571

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The interface state density of silicon metal‐oxide‐semiconductor (MOS) transistors operated at room, liquid‐nitrogen, and liquid‐helium temperatures is investigated using the conventional subthreshold slope technique. The magnitude of the interface state density found of the order of 1013–1014/eV cm2at liquid‐helium temperature, suggests that such states correspond to the localized states situated in the band tails below the mobility edge of the two‐dimensional subband. Moreover, the interface state densities found by the subthreshold slope have been confirmed using the dynamic transconductance technique.

ISSN:0021-8979    

DOI:10.1063/1.345572

出版商:AIP    

年代:1990

数据来源: AIP