摘要:

A new method of ionized antimony doping of silicon molecular beam epitaxial films has been investigated. Si films were grown on Si (111) substrates by evaporation of Si from ane‐gun evaporator in ultrahigh vacuum. Sb ions were generated with an electron impact ion source. Carrier concentration of doped layers, grown at a substrate temperature of 860 °C, can be accurately controlled over the range 1016–1020cm−3. Doping efficiency of Sb ions is 100%. Doping with ions in the range 130–1000 eV kinetic energy does not degrade the crystallographic or electrical quality of the films. For example, abrupt changes in the doping level of a composite film with three doped layers are given. The in‐depth Sb dopant profile of this film corresponds closely to the Sb ion doping schedule, which indicates that the surface segregation of Sb does not occur attendant ion doping.

ISSN:0021-8979    

DOI:10.1063/1.327993

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The energy gap in silicon and germanium is calculated as a function of the concentration of donor impurities. The results are compared with the available data from optical experiments and devices. Previous theories are critically reviewed.

ISSN:0021-8979    

DOI:10.1063/1.327994

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The effect of hydrogen on the Fe giant moment in dilute PdFe and the resulting single moment Kondo and RKKY interactions in PdHxFe is investigated by Mo¨ssbauer hyperfine techniques in an external magnetic field. The results show that within a large range of composition within the &agr;′ phase (hydrogen lattice liquid), &mgr;(Fe) remains constant at about 3.9&mgr;B, smaller than the 12.6&mgr;Bin dilute PdFe. The Kondo temperatureTKis found to increase with hydrogen, as determined from the usualX=&mgr;H/k(T+&Vthgr;) modification to the Brillouin functionB1(X) where &Vthgr;=4.5TK. The dynamic part of the impurity interactions leads to a spin‐glass–type spin‐spin relaxation, which produces a line broadening in a magnetic field much larger for the outer Mo¨ssbauer lines and with a maximum in field at aboutX=1. At higher concentrations (x=0.76), the saturation HF field decreases, indicating a possible orbital component on &mgr;(Fe); this conforms with certain recent calculations. Abovex=0.8, new Mo¨ssbauer lines are found, indicating the phase transitions and two‐phase regions &agr;′ → &bgr; and &bgr; → &agr;″with increasing hydrogen content.

ISSN:0021-8979    

DOI:10.1063/1.327995

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The quantum effect on the transverse magnetoresistance of degenerate piezoelectric semiconductors with the isotropic parabolic energy bands has been studied for the case where acoustic phonons are the dominant scattering mechanism. The calculation has been performed taking into account the inelasticity in the electron‐phonon scattering due to the finite energy of phonons involved. It is shown that both deformation‐potential and piezoelectric couplings play the same important role for the transverse magnetoresistance in strong magnetic fields B. These results are quite different from those of our previous work for nondegenerate semiconductors in which the acoustic‐phonon scattering due to the piezoelectric coupling contributes very insignificantly to the transverse magnetoresistance. Numerical results also show that transverse magnetoresistances for both couplings oscillate with the magnetic field owing to the degeneracy of the electron gas. However, the number of oscillations will decrease when the magnetic field increases.

ISSN:0021-8979    

DOI:10.1063/1.327996

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Velocity‐field curves forn‐type silicon on sapphire have been measured at fields up to 60 kV/cm using pulsedI‐Vtechniques and specially designed test structures. Successive etching was used to determine the dependence of drift velocity on distance from the silicon‐sapphire interface. Within experimental error, the drift velocity of electrons is found to saturate at the same value as in bulk silicon, although the field required to achieve saturation is greater than in bulk Si and increases with decreasing Ohmic mobility near the interface. Sample heating can have a large effect on the experiment. The results, which are important for the design of high‐speed SOSFET’s are explained using simple hot‐electron physics.

ISSN:0021-8979    

DOI:10.1063/1.327997

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Theoretical and experimental studies of the electron mobility and the free‐carrier absorption ofn‐type InP were carried out in the temperature range 77–300 °K. All major scattering processes and screening effects were taken into consideration. It was found that the experimental dependence of electron mobility and free‐carrier absorption on temperature and/or on carrier concentration can be consistently explained only when the effect of compensation is quantitatively taken into account. Convenient procedures are presented for the determination of the compensation ratio from the values of electron mobility and from the free‐carrier absorption coefficient. The high contribution of optical‐phonon scattering in InP limits the applicability of the free‐carrier absorption approach to electron concentrationn≳1017cm−3. Electron mobility, however, can be reliably employed for the determination of the compensation ratio forn≳1017cm−3at 300 °K andn≳1015cm−3at 77 °K.

ISSN:0021-8979    

DOI:10.1063/1.327925

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The temperature dependence of electron mobility of high‐purity LPE Ga1−xAlxAs layers (x<0.18) has been studied in the range 25–110 °K to measure the extents of alloylike and ionized impurity scattering. Values of the alloy scattering parameterEB(which may include a contribution from space‐charge scattering) determined for these samples were found to lie in the range 0.36–0.51 eV, the average being 0.44 eV. The compensation ratio was found to be about 2, and independent ofx.

ISSN:0021-8979    

DOI:10.1063/1.327926

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The degradation phenomena caused by dc and ac biasing in non‐Ohmic ZnO ceramics are studied from the viewpoints of voltage (V)‐current (I) characteristics, dielectric properties, and thermally stimulated current (TSC). As a result, it is concluded that the degradation caused by dc biasing is attributed to the asymmetrical deformation of Schottky barriers, due to ion migrations in Bi2O3‐rich intergranular layers and in the depletion layers of the Schottky barriers; and that the degradation caused by ac biasing is attributed to the symmetrical deformation of the Schottky barriers, due to ion migration in the depletion layers of the Schottky barriers. Also, the relationship between the thermal runaway life of non‐Ohmic ZnO ceramics and biasing conditions, such as biasing temperature and bias voltage, is obtained.

ISSN:0021-8979    

DOI:10.1063/1.327927

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The novel results reported in this paper pertain to the behavior of the moderate‐to‐low frequency reactance of Si and GaAsp‐njunction diodes as a function of the incident photon flux densityF. We have observed that the diode reactance, which is invariably capacitive under dark or low photon flux conditions, may turn inductive at a threshold photon flux densityFthdepending on the diode structure and the spectral characteristics of the incident radiation. Photoinductance values of greater than 100 &mgr;H/cm2were measured reproducibly at room temperature using a 1‐MHz signal in severalp+p‐n,n+‐p, andn+n‐pp+type Si diodes (dc open‐circuited) illuminated with argon ion (4880 A˚), He‐Ne (6328 A˚) lasers, and white light radiation sources operating at moderate‐to‐high photon flux densities. Specifically, the photon flux density was varied from virtually dark to about 20 times more intense as compared to the solar flux at air massm=2. Theoretically, an explicit inductive component is shown to originate in the conductivity modulated sectionlcmnof the base region when the photogenerated minority carrier concentration becomes comparable to that of majority carriers. The magnitude of photoinductive reactance is computed as a function of incident photon flux densityFand results are compared with experiment for an+‐pSi cell.

ISSN:0021-8979    

DOI:10.1063/1.327928

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

When addressed with a 1‐MHz sinusoidal or triangular wave signal, the on‐state of NbO2shows two regimes of conductance. The lower‐conductance regime occurs over the voltage range less than the holding voltage and shows, for the most part, superlinearI‐Vcharacteristics. Decay studies indicate that the time interval in this low‐conductance or lower‐current subregime is an inverse linear function of the on‐state mobile charge density. This study also indicates that the subsequent positive peak current is also an inverse linear function of the time interval in the lower‐conductance subregime of the previous cycle. The nonlinear lower‐current subregime of the on‐stateI‐Vcharacteristics is thus directly related to the decay of the charge density of the true on‐state, the decay being induced by a critical time duration of subholding voltage conditions. It is hence believed that the lower‐current regime is a consequence of a relaxation‐induced trapping phenomenon, and that the recovery of the high‐conductance true on‐state metal‐like regime is due to the field‐induced liberation of electrons from trapping centers. These data reinforce our earlier contention that both a critical charge concentration and a critical electric field intensity are inseparably necessary to maintain the on‐state in NbO2.

ISSN:0021-8979    

DOI:10.1063/1.327929

出版商:AIP    

年代:1980

数据来源: AIP