摘要:

p‐type GaSb and Ga0.8In0.2Sb layers were grown on GaAs substrates by the low pressure metalorganic vapor phase epitaxy technique, using silane as the dopant source. It was found that Si is a well behavedp‐type dopant in GaSb and Ga0.8In0.2Sb compounds. Secondary ion mass spectrometry measurements and Van der Pauw Hall measurements indicated that the compensation ratio (defined asNd/Na) of 2×1018cm−3dopedp‐type Ga0.8In0.2Sb layer is less than 0.25, whereas the compensation ratio is less than 0.1 for layers doped to <5×1017cm−3. Control ofp‐type doping level in the mid 1016cm−3–mid 1018cm−3range has been demonstrated. The effects of trimethylantimony mole fraction and the growth temperature on the Si incorporation behavior were also studied. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117130

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Using photoluminescence we have studied the effect of a low temperature ‘‘preanneal’’ stage on the intermixing of 3 nm Si0.7Ge0.3/Si quantum wells, implanted with silicon ions having energies up to 1 MeV and then exposed to rapid thermal annealing at 850 °C for 300 s. We find that an unwanted quantum well band gap increase in unimplanted samples after rapid thermal annealing can be reduced substantially from ∼30 to ∼5 meV due to the removal of grown‐in defects by preannealing at 630 °C for 24 h. Preannealed samples that were implanted and rapid thermal annealed showed at least the same band gap increase (up to 70 meV in these samples) observed for nonpreannealed samples. These results are understood in terms of significantly different activation energies for defect diffusion and quantum well intermixing and a nonlinear dependence of the energy shifts on defect concentrations. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117131

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Boron doping concentrations ≳6×1019cm−3were found to increase Si(001) growth ratesRSiat low temperatures while decreasingRSiat higher temperatures during gas‐source molecular beam epitaxy (GS‐MBE) from Si2H6and B2H6. In order to probe the mechanisms governing these effects, Si(001) samples withBcoverages &thgr;Branging from <0.05 to &bartil;0.5 ML were prepared by exposing clean Si(001)2×1 wafers to B2H6doses between 2×1017and 4×1020cm−2at 200–400 °C. The samples were then heated to 700 °C to desorb the hydrogen, cooled to 200 °C, and exposed to atomic deuterium until saturation coverage.D2temperature programmed desorption spectra exhibit &bgr;2and &bgr;1peaks due to dideuteride and monodeuteride desorption at 405 and 515 °C as well as newB‐induced peaks, &bgr;2*and &bgr;1*, at 330 and 470 °C. Increasing &thgr;Bincreases the area under &bgr;2*and &bgr;1*at the expense of &bgr;2and &bgr;1. Moreover, the totalDcoverage continuously decreases from &bartil;1.23 ML in the absence ofBto &bartil;0.74 ML at &thgr;B=0.5 ML. We propose that the observedB‐induced decrease in the Si*‐Dbond strength, where Si* represents surface Si atoms bonded to second‐layerBatoms, is due to charge transfer and increased Si* dimer strain. The Si* toBcharge transfer also deactivates Si surface dangling bonds causing the decrease in &thgr;D. These results are used to explain the GS‐MBE growth kinetics. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117132

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Current–voltage characteristics of AlGaN/GaN modulation doped field‐effect transistors at elevated temperatures are studied experimentally. The drain–source current and extrinsic transconductance are both found to decrease with increasing temperature. Decrease in mobility with increasing temperatures is considered to be one of the causes of the reduction in the current and transconductance. The capacitance–voltage characteristic reveals the absence of heat activated traps in the modulation doped layer. The physics underlying various high‐temperature operations of current–voltage characteristics is discussed. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117133

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Room‐temperature anodic oxidation (ANO) followed by rapid thermal nitridation in N2O was used as new method to prepare thin nitrided oxides. It was found that the ANO nitrided oxides demonstrate better interfacial property and breakdown endurance than rapid thermal oxidation (RTO) nitrided oxides. The concentration of nitrogen incorporated in ANO nitrided oxide is larger than that in RTO nitrided oxides. It is believed that the loose density and the existence of hydrogen related species in anodic oxides formed by room‐temperature anodization cause nitrogen to diffuse easier into oxide and pile up at Si/SiO2interface during N2O nitridation. In addition, the self‐readjustment of anodization current through the weak path in oxide is beneficial to thin gate oxides. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117134

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The coherent Stranski–Krastanov growth mode is used to create selfassembled InP islands on GaInP/GaAs(311)A surfaces. The resulting islands on (311)A surfaces have a base width distribution peaked in the range of 600–800 A˚ in contrast to a distribution peaked at 1200 A˚ for islands on (100) surfaces. In addition on the (311)A surfaces, there is a bimodal island height distribution peaked at 15 and 50 A˚. For the (311)A surfaces, the islands are significantly smaller and more dense (∼1010islands/cm2) than the islands formed on (100) surfaces (∼109islands/cm2). Despite these differences in the islands formed on the two surfaces, the growth occurs similarly for the two surfaces, with the formation of three different types of islands distinguished primarily by height. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117135

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A Si substrate purposely grown for Si‐based optoelectronic applications is described in this letter. The structure contains a built‐in Si/SiO2Bragg reflector which is prepared by multiple separation‐by‐implanted‐oxygen technique, whereinsitulow energy oxygen ion implantation is performed on molecular beam deposited Si to create alternating Si/SiO2epitaxial bilayers. The quality of the top Si layer was confirmed to be epitaxy‐ready after cross‐sectional transmission electron microscopy. Maximum reflectance at near normal incidence was over 90% for bilayer periods of 4 to 5. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117557

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report the formation of self‐assembling CdSe quantum dots during molecular beam epitaxial growth on ZnSe and ZnMnSe. Atomic force microscopy measurements on specimens with uncapped dots show relatively narrow dot size distributions, with typical dot diameters of 40±5 nm, and with a diameter‐to‐height ratio consistently very close to 4:1. Uncapped CdSe dots are unstable with time: their density was observed to drop by an order of magnitude in 10 days, with clear evidence of ripening observed for some dots. Photoluminescence from capped dots indicates exciton localization much stronger than in ZnCdSe/ZnSe quantumwells, due to the additional lateral confinement. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117558

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Self‐organized InSb dots grown by atomic layer molecular beam epitaxy on InP substrates have been characterized by atomic force and transmission electron microscopy. Measurement of high‐energy electron diffraction during the growth indicates a Stransky–Krastanov growth mode beyond the onset of 1.4 InSb monolayer (ML) deposition. The dots obtained after a total deposition of 5 and 7 ML of InSb present a truncated pyramidal morphology with rectangular base oriented along the ⟨110⟩ directions, elongated towards the [110] direction with {111}Blateral facets, with {113}/{114}/{111}Alateral facets in [11¯0] views, and (001) flat top surfaces. The mismatch between the dot and the substrate has been accommodated by a network of 90° misfit dislocation at the interface. A corrugation of the InP substrate surrounding the dot has been also observed. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117559

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The influences of microdefects and dislocations on the lattice parameters of undoped semi‐insulating GaAs single crystals were analyzed, and a novel nondestructive method for measuring stoichiometry in undoped semi‐insulating GaAs was established in this letter. The comparison of this method with coulometric titration indicates that the method of nondestructive measurements is indeed convenient and reliable. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117560

出版商:AIP    

年代:1996

数据来源: AIP