摘要:

Etching enhancement in through‐implanted SiO2has been characterized by nuclear‐deposited energy independently of implant conditions. An empirical expression has been proposed to describe the etching rate for any implantation. The enhanced etching has been related to the Si‐O vibrational frequency shift. Etching enhancement has been found to reflect the structural change in SiO2, and to be a good measure of degradation. The structural change of SiO2stops and the etching rate reaches a maximum for an ion dose corresponding to nuclear‐deposited energy larger than 3.4×1023eV/cm3. This energy is equal to the total SiO bonding energy (3.8 eV) in a unit volume of SiO2.

ISSN:0003-6951    

DOI:10.1063/1.101429

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The differences between excimer (≊30 ns pulse duration) and flashlamp‐pumped dye (≊500 ns pulse duration) laser planarization are examined for 1.5–2 &mgr;m thick gold films over SiO2layers. Test structures containing bar patterns (square waves) of 5000 A˚ peak‐to‐trough amplitude with spatial periods ranging from 10 to 100 &mgr;m were prepared and laser irradiated. A linear model is presented which described the time evolution of the film’s surface topography when melted with a dye laser pulse. Excimer laser planarization is found to be susceptible to evaporative recoil effects which may cause undesired pattern amplification.

ISSN:0003-6951    

DOI:10.1063/1.100772

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The material interface of a molecular beam epitaxy grown Al0.5Ga0.5As‐GaAs heterostructure is investigated on a cross‐sectional (110) cleavage plane using tunnel spectroscopy. The depletedn‐type region and the electron confinement layer adjacent to the interface are identified with local current‐voltage spectroscopy. The spatial width of these layers is close to 15 nm. The spectroscopy can be interpreted with the valence‐band offset in the interface, and a value of 0.35 eV is found for this quantity.

ISSN:0003-6951    

DOI:10.1063/1.100773

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Using deep level transient spectroscopy we have studied theDXcenter in a series of periodic GaAs/GaAlAs uniformly Si doped structures. The presence of theDXcenter is only detected when the structures do not exhibit superlattice behavior. This is understood by the fact that either theDXassociated level is resonant in the first conduction miniband (or above it) or that it does not exist because the original band structure of GaAlAs is destroyed by electron delocalization. Examination of the variation of the concentration ofDXcenters in periodic planar doped GaAlAs structures shows that this disappearance is due to a band structure effect, thus demonstrating that theDXcenter originates from a shallow‐deep instability of theL‐band effective mass state of the Si impurity due to intervalley mixing.

ISSN:0003-6951    

DOI:10.1063/1.100774

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Electron drift mobility longitudinal to hydrogenated amorphous silicon/silicon nitride multilayer structures has been measured by the time‐of‐flight method. Transient photocurrent shows a clear kink corresponding to the transit time. The room‐temperature electron mobility in multilayer structures is smaller by three or four orders of magnitude than that observed in bulka‐Si:H. The room‐temperature electron mobility decreases with decreasing well layer width at constant layer thickness of 13 A˚, while the activation energy of the mobility increases. The lifetime of electrons tends to increase when the well layer thickness is reduced.

ISSN:0003-6951    

DOI:10.1063/1.101478

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

AlxGa1−xAs 0.2<x<0.4 epilayers were grown by metalorganic vapor phase epitaxy in the temperature range of 850–950 °C. It has been experimentally shown that epitaxial growth at high temperatures enhances the free‐carrier concentration and causes unusual behavior of deep centers for Sn‐doped AlxGa1−xAs. From the temperature dependence of the Hall carrier density, and assuming multivalley conduction, an activation energy of the donor of 10 meV was deduced. Furthermore, these samples did not exhibit persistent photoconductivity. Besides, when all parameters of the epitaxy were kept constant, the aluminum fraction in the epitaxial layers slightly increases as the growth temperature increases.

ISSN:0003-6951    

DOI:10.1063/1.100775

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Clean surfaces of molecular beam epitaxially grown GaAs were exposed to diethylgalliumchloride (DEGaCl) and the resultant change was observed byinsitux‐ray photoelectron spectroscopy. At a substrate temperature of 300 °C, a self‐limiting reaction between DEGaCl and the surface resulted in one monolayer of Ga deposition which is believed to lead to atomic layer epitaxy of GaAs using DEGaCl. No appreciable increase of Cl or C was observed after exposure. Discussion on the mechanism of the self‐limiting reaction is also presented.

ISSN:0003-6951    

DOI:10.1063/1.100776

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Improvement of dielectric breakdown characteristics and hot‐electron‐induced interface degradation of metal‐oxide‐semiconductor capacitors having fluorinated ultradry oxides has been demonstrated. The fluorine is introduced through HF surface treatment of Si prior to oxidation. Secondary‐ion mass spectrometry data indicate that SiF distribution is peaked both at the surface of the oxide and at the SiO2/Si interface in the fluorinated ultradry oxide. The possible role of fluorine on the improvement of the dielectric characteristics will be discussed.

ISSN:0003-6951    

DOI:10.1063/1.101479

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Devices consisting of 100 parallel, modulation‐doped GaAs/AlGaAs wires, each about 40 nm wide, have been fabricated and tested at 4.2 and 77 K. The wires were created by ion milling a shallow grating into the doped AlGaAs layer. The mask for etching the grating was produced by x‐ray nanolithography, and lift‐off of Ti/Au. The grating period was 200 nm and the linewidth about 85 nm. Backgate bias or illumination was used to modulate the charge density in the wires. Conductance measurements at 4.2 K provide clear evidence of quasi‐one‐dimensional density of states. A corresponding modulation of the electron mobility, above and below values in the two‐dimensional system, was observed.

ISSN:0003-6951    

DOI:10.1063/1.100738

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

In this letter we present for the first time the observation of quantum‐confined transitions of a short‐period sawtooth doping superlattice in photocurrent and luminescence. The luminescence was investigated with different laser intensities. Due to the nature of the band modulation of sawtooth doping superlattices, the resonant energies for optical transitions are dependent on the intensity of the laser beam. We present a model, which incorporates both the Kronig–Penney energy dispersion and the self‐consistent intensity‐dependent internal field to explain the observed energy shift. Furthermore, the differences between photocurrent and luminescence measurements are discussed.

ISSN:0003-6951    

DOI:10.1063/1.100739

出版商:AIP    

年代:1989

数据来源: AIP