摘要:

Diamond crystallites were nucleated and grown from the vapor phase on silicon substrates previously processed into arrays of nanometer‐scale silicon wires. We found that the nanowires did not aid nucleation, and that the nucleation density on the nanowire base was very low (<104cm−2). Most importantly, we discovered that single diamond crystallites grew around the nanowires, infiltrating the nanowire arrays, forming new composite structures. This discovery clearly shows how inclusions can be trapped in vapor grown diamond crystallites, and challenges the common assumption that growth precursors on the diamond surface are relatively immobile. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114691

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A quantitative method to determine the profile of the residual stress along the depth of a highly boron doped silicon film is reported. First, the stress profile relative to the stress at the neutral surface of the film is obtained by measuring deflection ofp+silicon cantilevers with different etch depths. Second, the average of the residual stress is obtained by using a rotating beam structure. The stress profile is determined completely from these two calculations. One example of application by this method illustrates that most of thep+region is subjected to the tensile stress except for the region near the front surface. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114692

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report the behavior of steps and out‐of‐phase boundaries (OPBs) of 7×7 reconstruction on Si(111) during Si molecular beam epitaxy. During step‐flow growth, Si atoms are preferentially incorporated into the crystal at positions where steps are connected with OPBs on the lower terraces, resulting in sawtooth shaped steps. This heterogeneous advancement of steps causes OPBs to rearrange and thereby reduce in number. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114693

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Real time monitoring of the growth of plasma deposited transparent thin films by spectroscopic phase modulated ellipsometry (SPME) is presented. Two on‐line methods of determination of the refractive indexnand the film thicknessdare evaluated. The first one is based on the fast inversion of the Fresnel equations (0.2 s with a conventional PC 486 computer). Combining the measurements simultaneously recorded at two photon energies, a 5% relative precision is obtained on 5–6000 A˚ thick films even deposited at high deposition rate (32 A˚ s−1). On the other hand, a better precision can be obtained using a least squares fit procedure based on single photon energy SPME measurements. In the latter case, it is shown that the productndcan be determined with a 1% precision, up to 6000 A˚. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114694

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Apparent superstructures have been observed with scanning tunneling microscopy (STM) on well‐ordered Ag(110) surfaces. These superstructures are due to the discrete sampling of the atomic corrugation in STM. Such sampling effects may explain superstructures observed previously with STM on graphite surfaces. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114695

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The effects of doping on the kinetics of solid‐phase epitaxial growth of amorphous alumina have been studied. Amorphous aluminaAl2O3) thin films, 200–265 mm thick, were deposited on to (0001) sapphire substrates by electron‐beam evaporation. Iron or chromium atoms were uniformly doped into the films during deposition to cation concentrations below 5 cationic %. The kinetics of the epitaxial growth were studied at 800–1050 °C in flowing oxygen gas byinsitutime‐resolved reflectivity techniques as well as by ion backscattering and channeling techniques. A phase transformation sequence from amorphous through gamma to alpha alumina has been observed in all the undoped and doped films. The transformation from &ggr; to &agr; alumina is a thermally activated process with an activation energy of 5.0±0.2 eV, independent of the presence of dopants. However, the presence of dopants affects the overall transformation rate. Fe enhances while Cr slows the growth rate relative to the undoped case. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114696

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have developed a two‐component chemically‐assisted ion‐beam etching (CAIBE) technique for dry‐etching of high‐speed multiple quantum well (MQW) laser mirrors. This two‐component process relaxes several constraints in the dry‐etching of Al containing opto‐electronic device structures with Cl2alone. The strained 3×100 &mgr;m2In0.35Ga0.65As/GaAs undoped andp‐doped 4‐QW ridge waveguide lasers containing GaAs/AlAs binary short‐period superlattice cladding layers with cavities fabricated by this CAIBE technique demonstrate record direct modulation bandwidths of 24 GHz (Ibias=25 mA) and 33 GHz (Ibias=65 mA), respectively. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114697

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A normal incidence quantum well infrared photodetector consisting of asymmetric GaAs/AlGaAs quantum wells has been demonstrated. The detector uses electron intersubband transitions between bound to extended states in the step quantum well. The infrared photocurrent spectrum characterized using a glowbar monochromator source shows a photovoltaic response in the configuration of normal incidence. The peak wavelength is 10.3 &mgr;m and a detectivityD&lgr;*=3.7×108cm &sqrt;Hz/W was achieved atT=80 K. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114698

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have used cross‐sectional scanning tunneling microscopy to study interface structure in arsenide/phosphide heterostructures grown by gas‐source molecular beam epitaxy. High‐resolution images of a sample grown at 550 °C by interrupting the growth of GaAs at 200 A˚ intervals with a 40 s P2flux reveal phosphide interlayers of widths as large as 30 A˚ with lateral variations in structure over <100 A˚ length scales. Images of a similar sample grown at 450 °C exhibit narrower interlayers and a lower level of phosphorus incorporation. These samples have also been characterized by high‐resolution x‐ray diffraction and reflection high‐energy electron diffraction. Together, these studies provide direct information about nanometer‐scale grading and lateral nonuniformity of interfaces that can occur under these growth conditions. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114699

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We demonstrate the operation of a surface emitting light emitting diode. The wavelength of the emitted light can be tuned with the applied voltage. The device is based on ap‐GaAs andn‐Ga1−xAlxAs heterojunction containing an inversion layer in thepside and, GaAs quantum wells in thenside, and, is referred to as HELLISH‐II (hot electron light emitting and lasing in semiconductor heterojunction). The device utilizes hot electron longitudinal transport and, therefore, light emission is independent of the polarity of the applied voltage. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114700

出版商:AIP    

年代:1995

数据来源: AIP