摘要:

The dynamics of growth of CdTe by molecular beam epitaxy is studied by RHEED intensity oscillations. The transition to growth by step propagation is observed at lower temperature (i.e., the diffusion length is larger) on the Te‐rich (2×1) surface than on the Cd‐richc(2×2)–(2×1) one. A strong anisotropy is found, which suggests that growth islands are elongated in the [11¯0] direction. In addition, sublimation cannot be neglected, with at least two mechanisms with different activation energies. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113952

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

GaAs layers that contain small Fe‐based precipitates have been grown using molecular‐beam epitaxy. The layers were produced either by codepositing Fe during GaAs growth or by first depositing a thin layer of an Fe‐Ga alloy and then growing a capping layer of GaAs. Microstructural characterization of the layers was performed by using transmission electron microscopy. For those samples in which the Fe alloy layer was deposited, the layer disappeared after GaAs growth, leaving behind Fe‐containing precipitates distributed throughout the GaAs overlayer. Precipitates were also formed in Fe codeposited samples. The sizes and number densities of the precipitates were dependent on the growth method used, with mean diameters ranging from 21 to 47 nm and number densities from 1013–1015per cm3. The phase, orientation, and morphology of the particles were also dependent on the growth conditions used, with FeAs and Fe being observed. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113953

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A novel bistable phenomenon having both a high conductance on state and a high impedance off state has been observed in a forward biased delta‐doped GeSi/Si tunnel diode grown by molecular beam epitaxy. The bistable characteristics are attributed to the different mobile carrier densities in the delta‐doped layers, which leads to the switching of the band structure from a tunnel junctionlike alignment to ap‐i‐njunctionlike alignment or vice‐versa. An on/off conductance ratio larger than 106has been demonstrated for a modified diode structure. The device processing is technologically compatible to the current Si metal‐oxide‐semiconductor technology, making the device useful for a high speed, high density static random access memory cell. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113954

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The substitution of Ge atoms into ion implanted AlSb is investigated by extended x‐ray absorption fine structure spectroscopy. Our results reveal that in the as‐implanted material, the implanted Ge atoms are equally distributed between two specific sites, one surrounded by Al atoms and the other surrounded by Sb atoms. After annealing at 750 °C for 5 s, the coordination number of the Ge atoms increases from ∼3 to ∼4 indicating solid phase regrowth of the implantation induced amorphous surface layer. Moreover, in the annealed AlSb, the substitution of Ge atoms into the Al sublattice dominates with an estimatedGeAl]:[GeSb]∼0.8:0.2. These results suggest that Ge atoms act preferentially as donor species in AlSb. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113955

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A process is described for the deposition of anatase titanium dioxide films by reactive magnetron sputtering. The films have a porous columnar morphology with a high effective surface area making them well suited to be used as photocatalysts. Data are presented on the use of such films in the photocatalytic decomposition of gas phase pollutants in air. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113956

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report on the intentionaln‐type doping of the diluted magnetic semiconductor Zn1−xMnxSe using ZnCl2as the dopant source. Samples with varying Mn concentrations and carrier densities were grown by molecular beam epitaxy and characterized using Hall effect, x‐ray diffraction, and photoluminescence measurements. Net carrier concentrations in excess of 1018cm−3are readily obtained forx≤0.08. Useful carrier densities can be achieved for Mn concentrationsx≤0.15, above which the samples are highly insulating. The controlled doping of this alloy provides another material for use in the fabrication of wide gap semiconductor device structures. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113957

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A study of silicon oxide etch rate uniformity in a high density, rf inductively coupled system with an rf capacitively coupled substrate electrode is presented. By introducing spatial variation of rf coupling to the substrate, etch rate uniformity across the wafer can be altered from a profile that is ∼20% higher in the center to one that is ∼10% lower in the center. The effect of spatially varying rf coupling impedance to the substrate is dependent on substrate resistance. Predicted etch rate profiles are obtained with a two‐dimensional analytic model of the plasma source that is coupled to an equivalent circuit discretization of the electrode assembly, substrate, and sheath. Model results compare favorably with experimental measurements. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113958

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We studied the dependence of the thickness and stoichiometry of YBa2Cu3O7−xdeposited in an off‐axis pulsed laser deposition geometry on the background oxygen pressure and the distance from the target. We observe a biregional drop‐off in thickness with increasing axial distance, with the border between the two regions at 3–4 cm away from the target. The thickness was proportional to the deposition pressure raised to the 2/3 power, at axial distances greater than 4 cm. Atomic force microscope studies of the two regions showed the density of micron sized particles to be 2–5×104/cm2within the first region (closer to the target) with no such particles in the second region. The stoichiometric composition did not exhibit this biregional dependence. At an optimum oxygen pressure of 200 mTorr, we were able to obtain a stoichiometrically uniform region as large as 3×4 cm2. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113959

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Superconducting transition edge bolometers on micromachined silicon membranes have been fabricated. The optical response is 580 V/W at a time constant of 0.4 ms. The detectivityD* is 3.8×109(cm Hz1/2 W−1) at a temperature of 84.5 K and within the frequency regime 100<f<300 Hz. This is one of the fastest composite type bolometers ever reported. Upon thermal optimization, this type of detector should be competitive with state‐of‐the‐art quantum detectors. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113960

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Magnetic force microscopy of amorphous compressed Terfenol‐D films of micron thickness on both crystalline Si and glassy silica shows that their ferromagnetic domain structure is one dimensional and periodic. On Si the structure is aligned with respect to the easy elastic direction of the substrate. The square of the domain period is proportional to the thickness of the film. All facts indicate that the domain morphology in these films is determined by a substantial elastic contribution to the domain wall and film/substrate interaction energies. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113961

出版商:AIP    

年代:1995

数据来源: AIP