摘要:

A method for predicting the long term behavior of semiconductor devices in the low dose-rate ionizing-radiation space environment is presented. The operating conditions related to this environment are briefly reviewed. The new method consists of three major steps. The first step is the determination of the trap characteristics using the experimental recording of an isochronal annealing curve. The second step is the prediction of the isothermal annealing behavior deduced from the experimentally deduced trap characteristics. This approach makes it possible to avoid time-consuming isothermal measurements. As trapping and detrapping processes are independent, combining both processes by convolution, the last step, allows prediction of low dose-rate effects. Up to now, this accelerated characterization method has not been applied to electronic devices. An experimental application of the model to predict the long term behavior of a typical metal oxide semiconductor field effect transistor is given and the results, as well as the validity and the limitations of the model, are discussed. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364251

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We have measured the electrical and optical properties of blue light-emitting diodes (LEDs) based on III–V nitrides. The current–voltage characteristic is described by means of the relationI=I0 exp(&agr;V). In this equation &agr; is temperature independent, suggesting a process of conduction by tunneling, as was recently reported also for blue-green LEDs based on III–V nitrides [Appl. Phys. Lett.68, 2867 (1996)]. We explain the differences between blue and blue-green devices taking into account the tunneling process across semiconductor interfaces, in which a great number of defects is present. The light output intensity of the LED as a function of junction–voltage data reveals a dependence on the junction–voltage of the typeL=L0exp(qV/1.4 KT), indicating that the radiative recombination path is via deep levels located at the forbidden gap. Furthermore, we find that the light output–current characteristic follows a power law likeL∝Ip. From the analysis of data it appears that, contrary to expectations, the nonradiative centers are saturated at very low current values that are comparable to the values at which this saturation takes place in LEDs based on III–V arsenides with a low content of defects. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364294

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

A phosphorus-doped silica (SiO2:P) cap containing 5 wt&percent; P has been demonstrated to inhibit the bandgap shifts ofp-i-nandn-i-pGaAs/AlGaAs quantum well laser structures after rapid thermal processing. The intermixing suppression has been attributed to the fact that SiO2:P is more dense and void free compared with standard SiO2together with a strain relaxation effect of the cap layer during annealing. Band gap shift differences as large as 100 meV have been observed from samples capped with SiO2and with SiO2:P. Then-i-pstructure showed a higher degree of intermixing compared top-i-nstructure. This behaviour has been attributed to the rise of Fermi level in thendoped structure, through which the formation energy of Ga vacancies is reduced compared to thepdoped structure. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364295

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

It is proposed that direct formation of epitaxialCoSi2andNiSi2as the first phase, is due to the interlayer between the metal and silicon acting as a diffusion barrier, which decreases the metal concentration at the growth interface. Such concentration controlled phase selection (CCPS) is explained thermodynamically by utilizing the effective heat of formation (EHF) model. This approach is also used to explain silicide formation with metal alloys. Concentration controlled phase selection (CCPS) is not only applicable to silicide formation but should in general enable materials scientists to form phases with desirable properties, by controlling the concentrations of the reactants at the growth interface. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364252

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Hard amorphous hydrogenated carbon (a-C:H) films deposited by self-bias glow discharge were implanted at room temperature with 70 keV nitrogen ions at fluences between 2.0 and 9.0×1016N/cm2. The implanted samples were analyzed by positron Doppler broadening annihilation spectroscopy to determine the voids distribution. For samples implanted with 2.0×1016N/cm2the defect distribution is broader than the vacancies depth profile predicted by Monte Carlo simulation. For higher fluences we observed a reduction of the defect density. These results are discussed in terms of a competition between two processes: ion induced defects and structural modifications induced in the films due to ion implantation. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364296

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The electrical resistivity&rgr;of the intermetallicsYCo12B6andGdCo12B6has been measured in the temperature range of 80 K<T<250 K, which embraces the second-order magnetic phase transition. From the temperature derivatives of&rgr;(T), the critical exponent&agr;of the specific heats has been determined. We found that the values of&agr;are typical of a Heisenberg ferromagnet. The temperature derivatives of&rgr;(T)are compared with the specific heat measurements. Also, the physical implications of the results are discussed. ©1997 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.364282

出版商:AIP    

年代:1997

数据来源: AIP