摘要:

An approximate solution of the problem of the electron‐beam‐induced current contrast from point‐like defects in a semi‐infinite semiconductor is given, which differs from that of Donolato [Optik (Stuttgart)52, 19 (1978/79)]. The ‘‘strength of the defect’’ is characterized by an effective radius. The contrast is shown to be a nonlinear function of the strength of the defect. The results are in qualitative agreement with new experimental data of Ourmazd, Wilshaw, and Booker [inProceedingsofthe41stAnnualMeetingoftheElectronMicroscopySocietyofAmerica, edited by G. W. Bailey (San Francisco Press, San Fransisco, 1983), p. 142].

ISSN:0021-8979    

DOI:10.1063/1.334516

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Shallow boron‐doped junctions in silicon have been investigated by means of secondary ion mass spectrometry, scanning electron microscopy, transmission electron microscopy, spreading resistance profiling, and four‐point probe techniques. The junctions were formed by implanting BF+2ions inton‐type Si at the dose range of 1–5×1015ions/cm2, through a thin (25‐nm) screen layer of silicon dioxide. We have emphasized the higher dose range (3–5×1015ions/cm2) as it is more relevant to processes in the current level of device integration. The use of BF+2species and the screen oxide layer is necessary in order to form junctions whose depthsxj≤0.4 &mgr;m, when conventional annealing techniques are employed. We have also examined junctions that were activated in a rapid thermal annealing system that utilizes an incoherent light source. One of the main objectives of this study is to compare conventional and rapid thermal annealing techniques. We thus evaluate the results obtained by these two methods of annealing for both the junction depthxjand the sheet resistivityRs. Other relevant variables such as a low‐temperature (77‐K) implantation, surface amorphization by Si implantation, and preactivation annealing have also been examined and their effects are discussed. Based on the results of the present study, a mechanism for boron activation in silicon is discussed.

ISSN:0021-8979    

DOI:10.1063/1.334517

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Electron heating in silicon dioxide (SiO2) at electric fields ≲5 MV/cm is demonstrated using three different experimental techniques: carrier separation, electroluminescence, and vacuum emission. Gradual heating of the electronic carrier distribution is demonstrated for fields from 5 to 12 MV/cm with the average excess energy of the distribution reaching ≳4 eV with respect to the bottom of the SiO2conduction band edge. Off‐stoichiometric SiO2(OS‐SiO2) layers are shown to behave similarly to very thin SiO2(≲70 A˚ in thickness) with a transition occurring from ‘‘cool’’ to ‘‘hot’’ electrons as the conduction mechanism changes from direct tunneling between silicon (Si) islands in the SiO2matrix of the OS‐SiO2material to Fowler‐Nordheim emission into the conduction band of the SiO2regions. The relationship of electron heating to electron trapping, positive charge generation, interface state creation, and dielectric breakdown is treated. The importance of various scattering mechanisms for stabilizing the electronic field‐induced heating in the SiO2and preventing current runaway and impact ionization is discussed. Scattering may be due to disorder, trapped charges, and acoustical phonons, as well as longitudinal optical phonons.

ISSN:0021-8979    

DOI:10.1063/1.334518

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

It is shown that electric field at a strongly inverted or accumulated surface is uniquely related to surface potential, and is independent of other variables such as substrate doping and (in the metal‐oxide‐semiconductor context) insulator thickness or permittivity. Equivalently, junction potential is a sufficient determinant of the analogous electric‐field value in a grossly asymmetric junction, and this value is unaffected by forward bias and modest reverse bias. The field value in question is exponentially related to junction (or surface) potential, and this fact combined with the field‐continuity requirement and analytic treatment of high‐side field explains the saturated high‐side potential drop ofkT/q.

ISSN:0021-8979    

DOI:10.1063/1.334519

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The energy subbands of the two‐dimensional electron gas in the potential well at the heterointerface of the AlGaAs/GaAs heterostructures are calculated for different grading of AlGaAs composition. The concentrationnsoof the two‐dimensional gas in the AlGaAs/GaAs modulation‐doped structures with graded heterointerface is shown to increase with the increase in the grading lengthWGRat small values ofWGR. At large values ofWGRnsostarts to decrease because of the diminishing interface peak of the conduction‐band edge. Depending on composition and doping of the AlGaAs layer, the maximum value ofnsois achieved forWGRbetween 20 and 70 A˚. An increase in the concentration of the 2‐D gas may lead to a larger device transconductance and to a large current swing. The obtained results indicate that extremely sharp heterointerfaces are not required for modulation‐doped devices.

ISSN:0021-8979    

DOI:10.1063/1.334520

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Using valence‐band and core‐level photoemission spectroscopy (PES) and electrical device measurements, the effects of annealing on Au:n‐type (110) GaAs Schottky diodes fabricated in ultrahigh vacuum have been studied. Similiar trends in the annealing‐induced changes in the barrier height of Au:n‐type GaAs were found for 0.2 and 15 monolayer coverages as determined by PES and for thick film coverages (1000 A˚) as determined by current‐voltage (I‐V) and capacitance‐voltage (C‐V) measurement techniques. In each case, the barrier height was found to be stable for temperatures between 30 and 200 °C and between 300 and 500 °C; while a gradual decrease in the barrier height was found for annealing temperatures of 200–300 °C. These changes are correlated with the formation of a Au‐Ga rich layer at the interface during anneals at 200 to 300 °C. Leakage currents were found to dominate theI‐Vcharacteristics in the devices which were annealed above the Au‐Ga eutectic temperature. These peripheral leakage currents were eliminated by mesa‐etching the devices. This allowed more reliable barrier height determinations using device measurements for higher annealing temperatures than has been previously reported for the Au‐GaAs system.

ISSN:0021-8979    

DOI:10.1063/1.334521

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Epitaxial silicon films were grown on (100) silicon wafers at temperatures between 650 and 700 °C without the need of special cleaning procedures. Deposition rates were from 30 to 80 nm/min. The structure of films was analyzed by Rutherford backscattering, transmission electron microscopy, and secondary ion mass spectroscopy. The films were doped by ion implantation. Electrical activity, Hall mobility, and sheet resistivity of the doped layers were measured. Both structural and electrical characterization yielded results indistinguishable from good‐quality bulk wafers.

ISSN:0021-8979    

DOI:10.1063/1.334522

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Using the switching characteristic of a metal‐tunnel oxide‐semiconductor thyristor, a new method is developed to determine the tunneling transmission coefficient through a thin oxide layer and the aluminum‐silicon dioxide and silicon‐silicon dioxide potential barrier heights in the metal‐tunnel insulator‐silicon system. The effects of the surface state charge and large bias voltage on the tunneling transmission coefficient are discussed. It is found that the tunneling transmission coefficient and the aluminum‐silicon dioxide and silicon‐silicon dioxide potential barrier heights are very sensitive to the oxide thickness.

ISSN:0021-8979    

DOI:10.1063/1.334523

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Growth temperature (TG) dependence of the acceptor concentrations (NA) in Al0.1Ga0.9Sb grown by liquid phase epitaxy in a very wide growth temperature range (250–500 °C) was investigated. It was found thatNAvaries withTGdown to 350 °C asNA∝exp(Ea/kBTG) withEa=0.47 eV and that below 350 °CNAfluctuates depending highly on growth conditions. Acceptors in Al0.1Ga0.9Sb grown above 350 °C were concluded to be intrinsic. These observations were successfully made using the improved extremely low‐temperature growth process. The evaluation technique of measuring the impurity concentration in a thin epitaxial layer on the conductive GaSb substrate byC‐Vcharacteristics of metal‐insulator‐semiconductor structures was employed.

ISSN:0021-8979    

DOI:10.1063/1.335456

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Large dc current pulses, &bartil;2 &mgr;s long, are sent through 30–40‐nm‐thick Ni87Fe13films containing Ne´el walls. Wall displacements are seen for current densities ≥1.2×107A/cm2. Displacements reverse when current sense is reversed. Walls always move in direction of charge carriers in this electronlike material. Our results agree with a theory ofs‐dexchange interaction between walls and 4sconduction electrons. Hydromagnetic ‘‘domain‐drag’’ forces are too small in such very thin films to explain our data.

ISSN:0021-8979    

DOI:10.1063/1.334524

出版商:AIP    

年代:1985

数据来源: AIP