摘要:

The internal streaking contrast within ion beam synthesized &bgr;‐FeSi2(&bgr;) grains has been studied. The results show that this internal streaking contrast is caused by the interfaces between coexistent &bgr; order domains (ODs) which are 90° oriented to one another around [200]&bgr;. The interface between adjacent ODs is (200)&bgr;. The mechanism for the formation of order domain boundaries (ODBs) is attributed to the impingements of separately nucleated growing silicide nuclei during the process of ion implantation and subsequent thermal annealing. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115197

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

It is found that an ordered and air‐stable GaAs(111)A–(1×1)–Cl surface can be produced by chemical etching/passivation with dilute HCl solution. The synchrotron polarization‐dependent ClK‐edge x‐ray absorption near‐edge structure and x‐ray photoelectron spectroscopy studies showed that the surface is terminated with Ga–Cl bonds oriented along the surface normal. Low‐energy electron diffraction studies showed a bulklike (1×1) structure on the Cl‐terminated GaAs(111)A surface. The Cl termination eliminates surface band‐gap states caused by surface oxides. Photoluminescence measurements showed a dramatic increase in the near‐band radiative emission rate corresponding to reduction in the occupied surface band‐gap states. A reduction of surface gap states by Cl termination was confirmed by surface photovoltage measurements. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115198

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Studies of the thickness dependence on stress‐induced leakage current (SILC) have been performed in the thickness range of 41 to 87 A˚ for N2O‐annealed and O2‐grown oxides. N2O‐annealed oxide shows significantly reduced SILC leakage currents. Furthermore, SILC currents were found to increase with decreasing oxide thickness, as reported earlier. However, a ‘‘turn‐around’’ effect at ∼50 A˚ has been observed in these films. SILC currents begin to decrease when oxide thickness is scaled below 50 A˚. This turn‐around effect can be explained using the trap‐assisted tunneling model. For thicknesses equal or less than 41 A˚, defect‐related current and direct tunneling current become dominant over SILC current. Our results indicated that for N2O‐based oxides in the ultrathin thickness regime, stress‐induced leakage currents become less significant. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115199

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

It has been shown that irradiation with atomic hydrogen during the growth of GaAs in molecular beam epitaxy (MBE) promotes an ideal layer‐by‐layer two‐dimensional nucleation and step‐flow growth mode on GaAs(001) substrates, thereby resulting in atomically flat surfaces. Fundamentally important observations related to elementary processes have been presented based on the reflection high‐energy electron diffraction (RHEED) and atomic force microscopy (AFM) measurements. A growth model for the atomic hydrogen‐assisted GaAs MBE has been postulated. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115200

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

By photoluminescence measurements we find that at low temperature the linewidth of the excitonic luminescence broadens with increasing electron density in the wider well from a photoexcited type‐I‐type‐II mixed GaAs/AlAs asymmetric double quantum well structure, which even makes the excitonic linewidth at 77 K larger than at 300 K above a certain excitation intensity. We verify that the broadening is due to the scattering of two‐dimensional carriers to excitonic states. Based on the theory of the scattering of carriers to excitonic states, we calculate the broadening of the excitonic linewidth. Our experimental results are convincing for verifying the theoretical prediction. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115201

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Si(100) surfaces treated by ultrapure water with 5 ppb dissolved oxygen concentration after dipping in HF solution were examined by attenuated total reflection (ATR)–Fourier‐transform infrared (FT‐IR) spectroscopy, transmittance FT‐IR, and reflection high energy electron diffraction (RHEED). FT‐IR spectra and RHEED patterns depended on the rinsing time in the ultrapure water. The (111) and (110) facets appeared after rinsing for a long period of time (20–45 h) in 5 ppb dissolved oxygen concentration ultrapure water. It was suggested that the surface morphology depended on not onlypH value but also the amount of etching. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115202

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We present a microscopic analysis of the influence of the spatial correlations between local diffusion noise sources on the noise calculation in a submicron GaAsn+nn+diode under different applied voltages. The simulation is carried out using an ensemble Monte Carlo simulation. We demonstrate that in the case of submicron nonhomogeneous structures the use of the diffusion coefficient to characterize the local noise sources is not correct, specially under far‐from‐equilibrium conditions. The nonuniformity of the electric field and the nonstationary behavior of the electrons lead to significant changes in the spatial correlations with respect to the case of an homogeneous semiconductor. Therefore, the diffusion noise at the terminals must be calculated in terms of the correlations between the local noise sources. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115203

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We performed nitrogen atomic‐layer doping into GaAs grown by molecular beam epitaxy using nitrogen molecules (N2) cracked by a hot tungsten filament. While uniformly nitrogen‐doped GaAs layers show relatively weak nitrogen‐related photoluminescence lines, nitrogen atomic‐layer‐doped GaAs layers show a series of sharp and strong photoluminescence lines. The dominant photoluminescence line was observed at 1.4437 eV, where an exciton bound to the nitrogen isotropic traps has the highest binding energy. ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.115204

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

1/fnoise was measured inn‐channel power transistors following high field stressing and high temperature anneals. Negative bias anneals resulted in considerably higher noise than produced by positive bias anneals. Then the bias was switched between positive and negative, the noise level switched between a low and a high level. The noise did not correlate with either interface or oxide trapped charge, but can be explained in terms of border traps and charge compensation. These mechanisms may be sufficient to explain a wide range of noise results inn‐channel metal‐oxide‐semiconductor field effect transistors. ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.115205

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have measured Raman spectra of diamond with nanometer size, called cluster diamond. The Raman bands assigned tosp2andsp3clusters have been observed at around 1600 and 1322 cm−1, respectively. This result suggests that the cluster diamond slightly contains thesp2cluster. The Raman band assigned tosp3cluster is found to shift by −10 cm−1, compared with that of bulk crystal and to be asymmetric with some tailing toward lower Raman frequency. The observed Raman spectrum agrees well with that calculated by a phonon confinement model. The crystallite size of the cluster diamond estimated from the phonon confinement model agrees approximately with that estimated from x‐ray measurement. Raman spectroscopy gives some information about the crystallite size of diamond particles with nanometer size. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115206

出版商:AIP    

年代:1995

数据来源: AIP