摘要:

We report a double‐crystal x‐ray diffraction study of the relaxation of molecular beam epitaxy grown Si‐Si1−xGexstrained single layers and superlattices on (100) Si. The thermal stability of the heterostructures was investigated by annealing between 600 and 900 °C. Measurement of (400) rocking curves demonstrated that all the heterostructures were initially coherently strained and had excellent crystallinity. Upon annealing deterioration of the crystal quality and progressive relaxation was observed on some of the samples while on others no relaxation or loss of crystalline quality was detected. These observations are consistent with the mechanical equilibrium theory predicting the critical thickness for pseudomorphic growth of lattice mismatch materials. However, the concept of critical stress needs to be invoked to account for the stability of dilute Si1−xGexalloy layers on Si.

ISSN:0003-6951    

DOI:10.1063/1.100999

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A nearly pure subsurface layer of an implanted element was created using aluminum implantation into beryllium. In particular, post‐implant annealing of polycrystalline beryllium samples implanted with 200 keV aluminum caused a dramatic increase in the peak aluminum concentration as determined by Rutherford backscattering. The effect was observed for all three doses studied: 0.46, 1.1, and 4.6×1018Al/cm2. For the 1.1×1018Al/cm2case, cross‐sectional transmission electron microscopy of the annealed sample revealed a distinct subsurface layer with the structure of crystalline aluminum. Auger sputter profiles of individual grains showed the layer purity to be as high as 98 at. % aluminum. However, there were indications that the layer formation and/or purity were grain dependent.

ISSN:0003-6951    

DOI:10.1063/1.100977

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A photoeletronic bistable device with selectable light output channels has been fabricated for implementation in photonic switching and processing systems. The device is a variation of the vertical to surface transmission electrophotonic device. Output in the stimulated light emission mode was successfully obtained from different waveguide channels by external electronic switching. Output channels could be switched at a rate of 400 Mb/s. The potential versatility of this device has been experimentally confirmed in programmable or switchable optical interconnections.

ISSN:0003-6951    

DOI:10.1063/1.100978

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The Fermi level at the Ga oxide/GaAs interface has been unpinned by rf plasma cleaning the GaAs surface in H2and N2. Following plasma cleaning, a Ga oxide film is reactively electron beam deposited onto the substrate. Metal‐oxide‐semiconductor (MOS) capacitors fabricated on these structures show good high‐frequency capacitance‐voltage characteristics. This indicates that the density of interface states has been reduced to ∼1011eV−1 cm−2. The MOS capacitors are found to be stable in air after several months.

ISSN:0003-6951    

DOI:10.1063/1.100961

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Selective growth of GaAs using an Ar+laser beam is reported. The laser irradiation during growth in the substrate temperature range 400–525 °C forms a GaAs spot of 400 &mgr;m in diameter. The spot growth rate increases up to 1.3 &mgr;m/h with laser power and does not depend on the type of substrate conductivity. Temperature rise due to the irradiation is revealed to be 7° at 120 °C for the laser power of 500 mW (laser beam diameter 400 &mgr;m). A concentric circle pattern can be formed by diffracting a laser beam. These results strongly suggest that the growth rate enhancement arises from the photodissociation of metalorganic molecules.

ISSN:0003-6951    

DOI:10.1063/1.100962

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The use of surface charging of a thin dielectric film on a semiconductor during x‐ray photoelectron spectroscopic analysis has been investigated. The binding energy shifts measured from 1.5 nm SiO2/p‐Si and 4 nm Si3N4/n‐InP indicate that a positive surface potential can be induced by the loss of photoelectrons in the dielectric, whereas a controllable negative potential can be applied by flooding the sample with low‐energy electrons. The measurements of the resultant depth‐dependent potentials in the oxide and in the semiconductor give useful information on the dielectric/semiconductor structure. For example, the results obtained using this technique show that in the case of SiO2/p‐Si, the Fermi level of the semiconductor at the interface was not pinned but in the case of Si3N4/n‐InP, it was pinned at 0.3 eV from the conduction‐band minimum. Moreover, the charging potential associated with a local impurity in the sample structure can be used to estimate the depth location of the impurity. Finally, the measurement of the degree of charging also gives information on the insulating properties of the dielectric.

ISSN:0003-6951    

DOI:10.1063/1.101450

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The effects of hydrogenation and subsequent annealing on unintentionally doped GaAs layers grown directly on Si substrates by metalorganic chemical vapor deposition have been characterized by capacitance‐voltage measurements, Hall effect measurements, transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS). Significant reduction of the carrier concentration in the GaAs layers after hydrogen plasma exposure is obtained. TEM shows that the hydrogen plasma slightly etches the surface of the GaAs layers, and EDS demonstrates that the etched area becomes arsenic deficient and contains minute Ga particles. In addition, atomic hydrogen diffuses deeply along threading dislocations and microtwin interfaces into the GaAs layers and reacts with GaAs locally around the defects.

ISSN:0003-6951    

DOI:10.1063/1.100963

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Changes of midgap‐state profiles of light‐soaked undoped hydrogenated amorphous silicon are measured in the process of a 150 °C annealing by transient heterojunction‐monitored capacitance measurements. Monomolecular annealing kinetics are found to be suitable for explaining the results, and the thermal activation energy for annealing is determined at each energy position of midgap states. This activation energy decreases with an increase in the energy position measured from the conduction‐band edge.

ISSN:0003-6951    

DOI:10.1063/1.100964

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Epitaxial Si layers with low dislocation density were grown on GaAs substrates by pyrolysis using disilane. The dislocation density evaluated from SECCO etching (HF:H2SO4:K2Cr2O7=100 cc:50 cc:2g) was less than 104/cm2, which is lower by two orders of magnitude than that of the GaAs layer on Si substrates. We found that the electron mobility of Si layers on GaAs substrates could be raised by decreasing the growth rate and a high mobility value the same as that of a homoepitaxial layer was obtained, although the Si layers were contaminated by an arsenic impurity of 1018cm−3.

ISSN:0003-6951    

DOI:10.1063/1.100965

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A theoretical study of quantum interference phenomena in a T‐shaped semiconductor structure is presented. Transmission and reflection coefficients are computed by use of a tight‐binding Green function technique. As expected, the results resemble the well‐known solutions for the electromagnetic field in waveguides with the main difference that the penetration of the wave function of the electrons can be controlled by external voltages. We conclude that transistor action based on quantum interference should be observable in such structures, and we present general results for the functional dependences of the transmission coefficient which corresponds to a transconductance.

ISSN:0003-6951    

DOI:10.1063/1.100966

出版商:AIP    

年代:1989

数据来源: AIP