摘要:

We report contact resistances as low as 0.035 &OHgr; mm between the ohmic contact metal and the two‐dimensional electron gas channel in an AlGaAs‐GaAs modulation‐doped field‐effect transistor structure. The contact resistances are achieved by transient annealing of AuGe/Ni/Au, and are to our knowledge the smallest values reported to date for these structures at room temperature. Assuming no change in the semiconductor sheet resistivity under the metal contact, the calculated specific contact resistivity would be as low as 5×10−8&OHgr; cm2, however, the true figure is not known. Details of our contact study include varying temperature‐time cycles and heterojunction structures. Current‐voltage measurements at 77 K show ohmic behavior, revealing the destruction of the heterojunction barrier in the contact region. Preliminary Auger energy spectroscopy profiles support an intermixing of the metal and semiconductor constituents down through the original AlGaAs‐GaAs interface. We, therefore, propose a model where the current flows laterally from grains (formed during annealing) into the two‐dimensional electron gas.

ISSN:0021-8979    

DOI:10.1063/1.334330

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Conducting and transparent thin films (60 and 120 nm) of tin oxide were prepared by reactive rf planar magnetron sputtering of an undoped hot‐pressed polycrystalline tin oxide target onto unheated substrates. The effects of the oxygen partial pressure on the room‐temperature electrical properties of the films were studied. The properties vary markedly with, for example, the value of resistivity ranging from a high of ∼8×10−1&OHgr; cm to a minimum value of about 3×10−3&OHgr; cm. This minimum is the lowest value of resistivity reported for undoped films prepared on unheated substrates. These films have optical transmittances greater than 80% averaged between 850 and 550 nm.

ISSN:0021-8979    

DOI:10.1063/1.334331

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The overall kinetics of silicide formation from metal‐silicon reactions, like those of most solid state reactions, result from the interactions of specific kinetic effects and thermodynamic terms. The decrease in reaction rate which is observed when Ni‐Cr alloys substituted for pure Ni cannot be explained by changes in the thermodynamic driving force. Some alternative suggestions are proposed.

ISSN:0021-8979    

DOI:10.1063/1.334332

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A combination of measurements of electrical resistivity, Hall mobility, and phosphorus concentration by secondary ion mass spectroscopy has determined the value of the Hall scattering factor in P‐doped epitaxially grown Si. The Hall scattering factor is found to increase from a value close to unity at a P concentration around 1017cm−3, to ∼1.3 in the 1018–1019cm−3doping range. At higher doping levels it decreases and saturates to a value of ∼0.9 for doping levels higher than 1020cm−3.

ISSN:0021-8979    

DOI:10.1063/1.334333

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

An analysis is presented on the statistics of deep‐level amphoteric traps in insulators and at interfaces (insulator boundaries) in terms of the occupancy functions for neutral and ionized trapping centers as a function of free carrier injection and spatial distribution of centers. Amphoteric traps are postulated for bulk insulator traps, such as silicon nitride in nonvolatile, erase‐write, semiconductor memory structures. In addition, amphoteric traps may be observed at interfacial boundaries, such as SiO2‐Si3N4, SiO2‐Al2O3, Si‐SiO2, and insulator‐liquid with site bonding. Under free carrier electron injection we find the characteristic trapped‐charge centroid movement decreases for small values ofRn=&sgr;+n/&sgr;0n, the ratio of capture cross sections for ionized to neutral trapping centers. These results reduce to Arnett’s treatment for single‐occupancy trapping centers (Rn≫1). Efficient conversion of positive (unoccupied) to negative (double‐occupancy) charged centers occurs under free carrier electron injection withRn&bartil;1. An analogous situation exists for the reverse operation, namely, conversion of negative to positive charged centers under free carrier hole injection.

ISSN:0021-8979    

DOI:10.1063/1.334334

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Photoluminescence (PL) intensity onn‐type InP at room temperature is found to provide a convenient probe of the density of surface states in the upper part of the gap of InP. PL measurements are used to monitor the interaction phenomena occurring between an insulator (Al2O3, SiOx) and the InP substrate during the first stages of its deposition. Despite the use of a soft deposition technique, the insulator induces systematically interfacial defects in metal‐insulator‐InP structures. The nature of the insulator and, to a larger extent, the InP surface preparation and the substrate temperature (although kept below 150 °C) play a major role.

ISSN:0021-8979    

DOI:10.1063/1.334335

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Measurements of minority carrier traps produced in silicon by neutron irradiation at room temperature were performed using deep‐level transient spectroscopy (DLTS), and these results were compared with those in 2‐MeV electron‐irradiated silicon. One electron trap (Ec−0.29 eV) and one hole trap (Ev+0.43 eV) were observed in neutron‐irradiatedp‐ andn‐type silicon, respectively, which were also observed in the 2‐MeV electron case. Furthermore, it was found that the isochronal annealing behavior of these minority carrier traps between the neutron and the 2‐MeV electron case coincided with each other. The present results about minority carrier traps and previously reported ones about majority carrier traps indicated that the neutron damage was similar to the electron damage as far as the DLTS measurements are concerned.

ISSN:0021-8979    

DOI:10.1063/1.334336

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

We have examined the regrowth rate of single implants of electrically active elements in silicon in terms of a model of crystallization that considers the diffusion of charged dangling bonds. An asymmetry in the regrowth velocity as a function of dopant concentration is explained in terms of differences in the shifts of the Fermi level on the amorphous (a‐) and crystalline (c‐) sides of thea‐cinterface. This effect is consistent with an increased shift in the Fermi level in thea‐ layer at thea‐cinterface. The increased shift is in turn suggested to be produced by an increased concentration of charged dangling bonds resulting from the dopant concentration gradient.

ISSN:0021-8979    

DOI:10.1063/1.334337

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The relation between the distribution functions of relaxation times of equivalent Maxwell and Wagner systems is discussed. The distribution function of a Wagner system is calculated under the assumption that the distribution of the equivalent Maxwell system is given by the Davidson–Cole function.

ISSN:0021-8979    

DOI:10.1063/1.334338

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The influence of the quantum mechanical reflection on current‐voltage characteristics is analyzed for small semiconductor heterojunction diodes including a potential barrier. It is shown that negative differential resistance can arise under conditions where the energy of electrons coming to the potential barrier can be controlled by an external field.

ISSN:0021-8979    

DOI:10.1063/1.334339

出版商:AIP    

年代:1985

数据来源: AIP