摘要:

Shadow‐masked growth using organometallic vapor‐phase epitaxy allows the creation of nonplanar regions having smoothly varying profiles devoid of macroscopic facets. The shape of these profiles is independent of gas flow direction and stripe orientation, suggesting that they are determined by lateral gas phase gradients. It is proposed that the absence of facets is due to the unique growth regime underneath the shadow mask, where organic radicals combine with group‐III surface species, temporarily returning them to the vapor phase. This process has been simulated using a two‐dimensional finite‐element analysis that accurately describes the experimental behavior. Furthermore, this hypothesis predicts other experimentally observed phenomena. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359012

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

In this study investigations into silicon plasma deposition and etching using both a very high‐frequency plasma in dilute SiH4/H2near partial chemical equilibrium and the pulsed silane flow method are presented. Under the conditions used, simultaneous growth of microcrystalline silicon (&mgr;c‐Si:H) and etching of amorphous silicon (a‐Si:H) is observed. The results obtained support a &mgr;c‐Si:H growth model in which the net growth rate is regarded as the difference of a silicon deposition and an etch rate. By patterning amorphous silicon using laser crystallization it was possible to produce uniform and well resolved submicrometer microcrystalline silicon features. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359013

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Formation of aluminum‐silicon (Al‐Si) alloy/titanium nitride (TiN) layered structures and their electromigration (EM) performance have been investigated. The crystallographic structure of the TiN film changes with the sputter‐deposition conditions. A large negative substrate bias in reactive sputtering induces a structural transition in the TiN film. The crystal orientation normal to the film surface is easily controlled from the ⟨111⟩ to the ⟨200⟩ direction. The crystallographic orientation of the Al‐Si alloy film has been successfully controlled by the film deposition on an orientation controlled barrier TiN film. The Al‐Si alloy film grows epitaxially on TiN at the initial stage of deposition and this causes the Al‐Si alloy’s preferred orientation to the underlying TiN film. These layered structures with different levels of Al‐Si alloy preferred orientation have been subjected to EM tests, and the Al‐Si alloy film with stronger ⟨111⟩ orientation was found to have a longer EM lifetime. The best EM resistance has been obtained on Al‐Si alloy film with the strongest ⟨111⟩ orientation, which is achieved on a TiN film formed by the nitridation of a titanium (Ti) film. Thus, highly reliable interconnects can be obtained by improving the preferred orientation of Al‐Si alloy film using texture improved TiN film. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359014

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The electric power consumed by hot tantalum and tungsten filaments used to dissociate hydrogen molecules into hydrogen radicals was measured at filament temperatures of 2000, 2300, and 2500 °C and hydrogen pressures from 0.5–100 Torr. The measured power consumption at pressures above 30 Torr was well represented by a model that assumed thermodynamic equilibrium between H2and H near the filament. With decreasing pressure, however, the dissociation of H2shifted from an equilibrium‐controlled regime to a surface‐reaction‐rate controlled regime. The relationship between the power consumption and the pressure in the surface‐reaction‐rate controlled regime was correlated with the surface dissociation probability, which was determined to range from 0.18 to 0.94. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359015

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Dynamics of a superconducting bearing with a high‐Tcsuperconductor and a set of alternating‐polarity magnets are discussed. The superconductor used is prepared by the quench and melt growth process. The set of magnets levitates over the superconductor which is field cooled in liquid nitrogen. To construct a dynamic model of the superconducting bearing, responses for impulse forces given to the levitating magnets in vertical direction are investigated. Damped free‐vibration curves of the levitating magnets are observed. Dynamic stiffness and viscous damping coefficient can be defined by using the periodical vibration curves. It is also found that the stiffness and the damping coefficient depend on the width of a bar magnet. The resultant energy loss of the superconducting bearing is evaluated by using the force‐displacement relationship and Bean’s critical state model [Phys. Rev. Lett.8, 250 (1962)]. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359016

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The growth conditions of undoped InGaAsP layers grown on GaAs0.61P0.39substrates and effects of Te and Zn‐doping on electrical and optical properties have been examined in detail. The narrowest full widths at half‐maximum (FWHM) of photoluminescence (PL) spectra were measured to be 40 meV at 300 K and 12 meV at 8 K for an undoped InGaAsP sample with a background electron concentration of 2×1016cm−3. Room‐temperature carrier concentrations in the range of 1.8×1017–3.4×1018cm−3forn‐type dopant and 1.6×1017–2.8×1018cm−3forp‐type dopant are obtained reproducibly. The 50 K PL spectra of Zn‐doped layers show three distinctive peaks and their relative intensities change with various hole concentrations. Visible light‐emitting diodes (LEDs) emitting at 619 nm and employing the InGaP/InGaAsP/InGaP double‐heterostructure (DH) grown on a lattice‐matched GaAs0.61P0.39substrate have been fabricated. The DH LEDs are characterized by current‐voltage (I‐V) measurement, electroluminescence (EL), light output power, and external quantum efficiency. A forward‐bias turn‐on voltage of 1.8 V with an ideality factor of 1.3 and a breakdown voltage of 16 V are obtained from theI‐Vmeasurements. The emission peak wavelength and FWHM of room‐temperature EL spectra are around 619 nm and 48 meV (15 nm) at 20 mA, respectively. The light output power of the bare diodes is as high as 0.32 mW at a dc current of 100 mA and an external quantum efficiency of 0.22% is observed. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359017

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The effects of the substrate biasVBSon the parameters of random telegraph signals (RTSs) in submicrometer siliconp‐channel metal–oxide–semiconductor transistors are analyzed. The fractional RTS amplitude increases slightly for more positiveVBS, suggesting a close connection with the capture cross section of the corresponding near‐interface oxide trap. A strong exponential dependence of the capture time constant on the drain currentIDis observed, which can be explained by the transverse‐field dependence of the hole capture cross section. The emission time constant on the other shows only a weak dependence onVBS, orID. Finally, the corresponding low‐frequency noise peaks at constant frequencyfare studied in detail; excellent agreement is observed between the theoretical Lorentzian spectrum and the experimental peaks. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359018

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The concept of homojunction internal photoemission far‐infrared (FIR) detectors has been successfully demonstrated using forward biased Sip‐i‐ndiodes at 4.2 K. The basic structure consists of a heavily doped IR absorber layer and an intrinsic (or lightly doped) layer. An interfacial workfunction between these regions defines the long‐wavelength cutoff (&lgr;c) of the detector. Three types of detectors are distinguished according to the emitter layer doping concentration level. Our model shows that high performance Si FIR detectors (≳40 &mgr;m) can be realized using the type‐II structures with a tailorable &lgr;c, in which the absorber/emitter layer is doped to a level somewhat above the metal‐insulator transition value. Analytic expressions are used to obtain the workfunction versus doping concentration, and to describe the carrier photoemission processes. The photoexcitation due to free‐carrier absorption, emission to the interfacial barrier, hot‐carrier transport, and barrier collection due to the image force effect, are considered in calculating the spectral response and quantum efficiency as functions of device parameters for Sin+‐istructures, leading to a detailed photoresponse analysis of type‐II detectors. These results are useful for the design and optimization of type‐II detectors. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359019

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The results of a study of the optical and electrical performance ofP‐on‐nHgCdTe heterojunctions, with a linear gradient in composition, are presented. First presented is a solution of the one‐dimensional continuity equation which includes the spatial dependencies of the material properties, such as absorption coefficient, band gap, and intrinsic carrier concentration, in the graded layer. Using the above solution, diodes with different grading profiles (and hence different electric fields), but with the same cutoff wavelength, are compared. The advantages of the built‐in electric field formed by the grading in composition are presented and discussed. It is shown that the major consequence of the electric field is the reduction of the effects caused by the imperfect CdTe/HgCdTe interface at the backside. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359020

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The injection of point defects into the silicon substrate consecutive to a solid state reaction between nickel and silicon was studied by transmission electron microscopy. By observation and determination of the density and size of interstitial type dislocation loops in the substrate at the different steps of the reaction, we could estimate that one interstitial is injected per 5000 nickel atoms. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.359021

出版商:AIP    

年代:1995

数据来源: AIP