摘要:

In this work, we propose the materialInNxAsyP1−x−y(InNAsP) on InP for long-wavelength laser applications, where the unique feature of the smaller lattice constant of nitrides together with the large electronegativity of nitrogen atoms has been utilized in reducing the system strain while increasing the conduction-band offset by putting N into a compressively strained material system. InNAsP/In(Ga)(As)P strained quantum well (QW) samples were grown by gas-source molecular beam epitaxy with a rf nitrogen plasma source. Very sharp and distinct satellite peaks as well as Pendellosung fringes are observed in high-resolution x-ray rocking curves for these QWs, indicating good crystalline quality, lateral uniformity, and vertical periodicity. Photoluminescence (PL) measurements on InNAsP/InP single QWs with different well widths as well as on InNAsP/InGaAsP multiple QWs reveal strong PL emissions in the range of from 1.1 to 1.5 &mgr;m, demonstrating their suitability for long-wavelength applications. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121000

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Silicon was pulse biased to−50 kVin a nitrogen plasma generated by microwave excitation in electron cyclotron resonance mode. Nitrogen ions from the plasma were accelerated in the electrical field and implanted into the silicon. Cross-section transmission electron microscopy showed that the resulting surface layer was amorphous. Tempering at 1500 K led to the formation of a 25 nm thick continuous crystalline film of&agr;-Si3N4buried under a 50 nm thick amorphous surface zone. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121001

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Photocrystallization of amorphous selenium(a-Se) films under illumination by polarized light with 632.8 or 647.1 nm wavelength has been studied by Raman spectroscopy. Preferential orientation of trigonal crystalline, selenium(t-Se) obtained as a result of photocrystallization has been observed, threefoldcaxis oft-Se being oriented perpendicular to the direction of the polarization of the illuminating light. Although the mechanism of polarization-dependent photocrystallization seems to be optical in origin, an alternative, essentially thermal, mechanism of the polarization-dependent photocrystallization ofa-Se is discussed. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121002

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Electric field-induced deformation modes, which are considered one of the causes of the hysteresis in the V-T response of polymer dispersed liquid crystal (PDLC), were investigated. We constructed model PDLC cells with varied alignment treatments at the interface of the liquid crystal droplets. The electric field-induced deformation modes of the liquid crystals in the model cells were analyzed by polarized microscope observations. Our results suggested a possible way to hysteresis-free PDLC devices. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121003

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The conditions for the self-organized formation of ordered hexagonal structures in anodic alumina were investigated for both oxalic and sulfuric acid as an electrolyte. Highly ordered pore arrays were obtained for oxidation in both acids. The size of the ordered domains depends strongly on the anodizing voltage. This effect is correlated with a voltage dependence of the volume expansion of the aluminum during oxidation and the current efficiency for oxide formation. The resulting mechanical stress at the metal/oxide interface is proposed to cause repulsive forces between the neighboring pores which promote the formation of ordered hexagonal pore arrays. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121004

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Using first-principles total-energy calculations, we investigated the atomic structure of a very thin Ti film on Si(001) and their intermixing. Our calculations show that the Ti film forms a pseudomorphic body-centered-tetragonal structure on Si(001). We found that intermixing of Ti and Si atoms energetically favors the formation of aC49-TiSi2phase. We propose a plausible explanation of how theC49-TiSi2phase and the interfacial structure between C49 phase and Si(001) are formed. We discuss why the transformation of the C49 phase into the C54 phase is inhibited when theTiSi2dimensions reach the submicron region. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121005

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

It has been demonstrated that Si substitution in aPbTiO3target helps to avoid the formation of a pyrochlore phase, which otherwise occurs during fabrication of the films directly on Si(100) by the pulsed laser deposition technique. The films are perfectlyc-axis oriented. Moreover, the ferroelectric properties ofPbTiO3are not affected by Si substitution. As silicon helps the realization of the films at low substrate temperature, the Pb/Ti ratio is maintained close to 1 and the loss factortan &dgr;in the range of 0.02–0.05. Thus, the integration of nonvolatile ferroelectric random access memory on semiconductors is shown to be possible in a reliable, cost effective, and simple manner. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121006

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

This work deposits(Pb1−xLax)(ZryTi1−y)1−x/4O3(PLZT) thin films, possessing good ferroelectric properties(Pr=14.4 &mgr;C/cm2),onPt/Ti/SiO2/Sisubstrates, usingSrRuO3perovskite as bottom electrodes. Precoating a metallic Ru layer onPt/Ti/SiO2/Sisubstrates prior to depositingSrRuO3bottom electrode further improves the film electrical properties. The optimum ferroelectric properties achieved arePr=25.6 &mgr;C/cm2,Ec=47.1 kV/cm,and&egr;r=1204.Analyzing the elemental depth profiles using secondary ions mass spectroscopy reveals that the presence of the metallic Ru layer effectively suppresses the outward diffusion of Ti and Si species. The interdiffusion between theSrRuO3layer and the subsequently deposited PLZT is also substantially reduced, an effect that is presumed to be the primary factor in improving ferroelectric properties for PLZT thin films. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121007

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

We have made ferroelectric memory capacitors by depositing aSrBi2Ta2O9thin film on a Si substrate separated by an ultrathin buffer layer of silicon nitride film. The hysteresis in the capacitance–voltage curves suggests a sizable memory window of 2 V with a programming voltage swing of±7 V.The switching time is estimated to be on the order of nanosecond based on the results of a one-shot pulse experiment. The results from the fatigue test indicate a slight degradation of the memory window after1011switching cycles. These properties are encouraging for the development of ferroelectric memory transistors. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121008

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Tantalum oxide films were deposited on Si substrates by chemical vapor deposition using the precursorTa[N(CH3)2]5,and an oxidizing agent—O2,H2O,or NO. Temperatures ranged between 400 and 500 °C and total pressures between10−3and 9 Torr. NO did not lead to satisfactory film growth rates. Insignificant(<1 at. &percent;)N and up to a few percent C are incorporated whenO2is the oxidant and the total pressure is in the Torr regime. In the milliTorr regime, theTa2O5films, grown using eitherO2orH2O,contain readily detectable amounts of C and N. For the films grown withO2in the Torr regime, leakage currents were significantly lowered when the flow rate ofO2increased from 100 to 900 sccm. ©1998 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.121009

出版商:AIP    

年代:1998

数据来源: AIP