摘要:

Using double crystal x‐ray diffractometry (XRD) and transmission electron microscopy (TEM), the annealing effects on heavily carbon‐doped GaAs films were studied. From isochronal annealing, the evolution of compressive strain in carbon‐doped GaAs films was observed by XRD. From cross‐sectional TEM, unusual misfit dislocations with extra‐half planes on the GaAs side were observed in the sample annealed at 900 °C for 30 min in addition to normal misfit dislocations with extra‐half planes on the film side. A possible mechanism for the formation of such misfit dislocations is proposed based on the over‐relaxation of misfit strain in the film. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114975

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Data are presented on the 300 K photopumped (pulsed) laser operation of a visible‐spectrum (&lgr;=650 nm) AlAs–AlGaAs/InAlP–InGaP quantum‐well heterostructure (QWH) crystal that utilizes high‐index‐contrast AlAs‐native‐oxide/Al0.6Ga0.4As distributed Bragg reflector mirrors. The mirrors are formed by the lateral oxidation (H2O+N2, 425 °C) of two sets of four ‘‘buried’’ AlAs layers that are separated by Al0.6Ga0.4As. These mirrors, which create a high‐Qcavity in the vertical direction, ‘‘sandwich’’ a one‐wavelength InAlP–InGaP QW active region, thus forming a compact microcavity that ‘‘tunes’’ the carrier scattering and recombination into a narrow spectrum (∼25 A˚) and supports laser operation in the vertical direction. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114976

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Previous determinations of Landau level lifetimes in GaAs/AlGaAs heterostructures from saturation cyclotron resonance measurements have been confused by heating effects. We have utilized a ps free electron laser to show that for samples with sheet concentration less than 3×1011cm−2, true saturation of cyclotron resonance is observable at high magnetic fields, in the presence of polaron nonparabolicity. However, at higher concentrations, the polaron is screened and saturation is no longer possible. At low magnetic fields (i.e., long wavelengths) where the polaron nonparabolicity is negligible, saturation is not possible for any sheet density. It is confirmed that the lifetime of the first excited Landau level has an inverse dependence on carrier density. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114977

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Direct current in semiconductor is theoretically shown to be capable of doubling the frequency of the incoming optical radiation. The second order susceptibility, proportional to the current is calculated to be in the 10−14−10−13m/V range. Applications of the novel phenomenon in probing and mapping of the current in semiconductor devices are considered. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114978

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have studied the defect engineering in metalorganic vapor phase epitaxy InxGa1−xAs by controlled oxygen doping. Diethylaluminum ethoxide (DEALO) was used as an oxygen precursor to provide the intentional deep level incorporation. DEALO doping in InxGa1−xAs:Si withx≤0.25 resulted in the reduction in carrier concentrations. The Al and O incorporation with a DEALO mole fraction was weakly dependent on alloy composition forx≤0.25. The degree of electrical compensation, however, decreased as the In content increased at the same oxygen content. Deep level transient spectroscopy investigations on a series of InxGa1−xAs:Si:O samples withxranging from 0 to 0.18 reveal a set of oxygen‐derived deep levels, similar to those found in DEALO‐doped GaAs. These characteristic deep levels appear to remain at a relatively constant energy with respect to the valence band, as compared to the rapid decrease in the conduction band of InxGa1−xAs withx. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114979

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Single‐crystal AlN grown on Al2O3is found to be wet etched by AZ400K photoresist developer solution, in which the active component is KOH. The etching is thermally activated with an activation energy of 15.5±0.4 kcal mol−1, and the etch rate is found to be strongly dependent on the crystalline quality of the AlN. There was no dependence of etch rate on solution agitation or any crystallographic dependence noted, and the etching is selective over other binary group III nitrides (GaN, InN) and substrate materials such as Al2O3and GaAs. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114980

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have studied the mechanism of Be incorporation in InP homoepitaxial films grown by metalorganic molecular beam epitaxy. The actual Be concentration in the films reaches 1–2×1019cm−3while the hole concentration saturates at a lower value &squflg;∼2×1018cm−3in our case). The measured lattice mismatch between film and substrate depends both on growth temperature and Be flux. The resulting changes in morphology suggest that the excess Be forms microclusters in the films grown at higher temperatures—due to the higher surface mobility, leading to the growth of oval defects. Be rejection to the surface is also observed. The surfaces of samples with no cap layer present a granulation which may be related to the formation of a new phase like Be3P2. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114981

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The luminescence energies of a variety of crystalline silicon nanostructures are calculated using a time‐dependent tight‐binding technique. The calculated energies are compared with measured values for porous silicon samples to determine the geometries of the regions in which electron‐hole recombination occurs. We observe a correlation between luminescence wavelength and nanostructure which is consistent with the porosity changes during the etching process. We conclude that porous silicon samples which emit visible light are composed of small crystallites, and that the active regions in longer wavelength emitters are wirelike structures. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114982

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We deposited tantalum nitride (TaN) films by low‐pressure metalorganic chemical vapor deposition (LP‐MOCVD) using a new precursor tertbutylimidotris(diethylamido)tantalum (TBTDET). Strong Ta–N double bond in the precursor preserved the ‘‘TaN’’ portion during the pyrolysis process. This method has yielded low‐resistivity films. It changed from 10 m&OHgr; cm (deposited at 500 °C) to 920 &mgr;&OHgr; cm (obtained at 650 °C). The carbon and oxygen concentrations were low in the films deposited at 600 °C, as determined by x‐ray photoelectron spectroscopy. Transmission electron microscopy and x‐ray diffraction analysis indicated that the as‐deposited films exhibited polycrystalline structures with the lattice constants close to the bulk TaN value. The TaN barrier layer was successfully applied as a glue layer for CVD tungsten (W) metallization schemes. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114983

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Two deep electron traps induced by lattice mismatch in relaxed GaAs1−xSbxlayers (x=0% to 3%) grown by liquid phase epitaxy (LPE) on GaAs substrates have been revealed by means of deep‐level transient spectroscopy. One of the traps, that shows nonstandard, logarithmic capture kinetics and whose energy level is tied to the valence‐band edge, has been related to electron states associated with &agr; dislocations. The other trap has been attributed to the EL2 defect and possible reasons of its unexpected formation in the LPE‐grown layers are briefly discussed. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114984

出版商:AIP    

年代:1995

数据来源: AIP