摘要:

The Rh/n‐GaAs contacts with and without sulfur passivation were examined. It was demonstrated that passivation results in contacts of better quality and improved thermal stability. The passivated contacts had higher barrier height, lower reverse current, and lower ideality factor. The formation of thermally stable S–S, S–Ga, and S–As bonds at the GaAs surface, suppression of thermally generated defects, and possible modification in the charge and structure of native oxide were used to explain the observations.

ISSN:0734-211X    

DOI:10.1116/1.588732

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

We report results of a scanning tunneling microscopy investigation on the reconstruction of GaP(001) surfaces. We have observed a 4×2 structure, accompanied locally withc(8×2) domains, at a surface prepared by using ion sputtering and annealing method. On the contrary, both 2×4 [with localc(2×8)] and 4×2 [with localc(8×2)] structures are obtained by hydrogenation followed by annealing. The former consists of a unit structure of three P dimers plus one dimer vacancy, whereas the latter is a parallel arrangement of zig–zag‐chained structures along the [110]direction. It has been shown that the surface hydrogenation before annealing induces new types of reconstruction.

ISSN:0734-211X    

DOI:10.1116/1.588733

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

ISSN:0734-211X    

DOI:10.1116/1.588734

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

ISSN:0734-211X    

DOI:10.1116/1.588735

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

ISSN:0734-211X    

DOI:10.1116/1.588736

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Shortly after World War II, Sir Charles Oatley initiated research at the Cambridge University engineering laboratories on what has evolved into the modern scanning electron microscope. While much of the research was actually conducted by research students under Oatley’s supervision, he continually provided ideas, resources, and encouragement. He then was instrumental in having this instrument commercialized. His students often continued in the field for some time, making contributions both to the instrument and to its applications that led to improved performance and wider acceptance. This article attempts to capture some of the accomplishments of Sir Charles Oatley as seen by those who worked closely with him. The author believes that Sir Charles deserves the title: ‘‘Father of the Modern Scanning Electron Microscope.’’

ISSN:0734-211X    

DOI:10.1116/1.588737

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Selected examples of the application of scanning probe methods for the fabrication, characterization, and testing of electronic and magnetic devices are presented. In particular, promising combinations of conventional photolithography or e‐beam lithography with scanning probe methods are described. The combination of atomic‐scale self‐organization processes with scanning probe microscopy and manipulation experiments possibly can lead to a novel class of atomic‐scale devices which could be fabricated on a reasonable time scale.

ISSN:0734-211X    

DOI:10.1116/1.588738

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

There has been steady progress in understanding the propagation of low‐energy, ion‐induced damage into semiconductor substrates. The availability of specifically designed heterostructure substrates allows us to trace the profile of damage into the material. A number of experiments, together with theoretical simulations, have confirmed the important role played by fortuitous channeling of ions, deep into the material (e.g.,>1000 Å deep for incident ions energies ∼300 eV). Recent experiments have also shown the importance of rapid diffusion of ion‐created defects. Using a model that includes the effects of both channeling and defect diffusion, channeling and diffusion in ion damage (CHANDID), we have deduced a room‐temperature diffusion constant ofD∼1×10−15cm2/s. This is an extremely high value for diffusion at room temperature, and is more characteristic of diffusion taking place at temperatures of a few hundred to a few thousand degrees centigrade. One cause of this high value ofDmay be attributed to radiation enhanced diffusion: the creation of excess electrons and holes during the etch process whose subsequent nonradiative recombination transfers momentum to the defects. Preliminary experiments, which monitor the effects of above band‐gap illumination during ion bombardment, validate this picture. Such understanding, of intrinsic importance, can be used to design material and device structures in which the effects of ion damage may be mitigated.

ISSN:0734-211X    

DOI:10.1116/1.588739

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Several new wet and dry etch processes required for fabrication of microdisk lasers in the III nitrides have been developed. ICl/Ar electron cyclotron resonance plasmas produce etch rates of 1.3 μm/min for GaN and 1.15 μm/min for InN at 1000 W microwave power and 250 W of rf power. These rates are substantially faster than previously investigated Cl2/Ar or CH4/H2plasma chemistries. Selectivities of 5–6 over AlN are obtained for these materials. Wet chemical etching of AlN and InXAl1−XN in KOH‐based solutions was found to be a strong function of etch temperature and material quality. The activation energy for these materials was in the range 2–6 kcal/mol, typical of diffusion‐controlled processes. The KOH solutions did not etch GaN or InN at temperature as high as 80 °C.

ISSN:0734-211X    

DOI:10.1116/1.588740

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The free Cl2thermal etching of InGaAs/InP was characterized for the fabrication of quantum well dots (QDs). The effects of mask shape on the three‐dimensional structure of the dot was investigated. Quantum dots with dimensions as small as 56 nm were fabricated using electron beam lithography and free Cl2etching. The dots were characterized using scanning electron microscopy and low temperature photoluminescence (PL). Metalorganic chemical vapor deposition (MOCVD) regrowth of InP on quantum dots of different mask shapes was investigated. The effect of non‐radiative recombination at the etched sidewall was evaluated through the normalized intensity of the PL. A red shift of the PL peak with decreasing dot sizes was observed for the as‐etched structures and attributed to the effect of residual compressive biaxial strain on the InGaAs layer. Free Cl2etching is an important etch technique forinsituetch and regrowth processes due to the high quality of the etched interface and the ability to perform selective area regrowth with a SiO2mask still present.

ISSN:0734-211X    

DOI:10.1116/1.588741

出版商:American Vacuum Society    

年代:1996

数据来源: AIP