摘要:

The current‐voltage characteristics of microfabricated field emitters following inert gas ion bombardment have been investigated and correlated with changes in the electron‐emission spatial distribution. The combination of glow discharge treatments in hydrogen and neon cause contaminant removal and mild emitter tip sputtering, leading to increases in the emitting area and significant improvements in the uniformity of the electron emission between tips in emitter arrays. The improved uniformity of the electron emission appears to be associated with a net smoothing of the emitter tip surfaces through the removal of field‐enhancing protuberances by the inert gas ion bombardment.

ISSN:1071-1023    

DOI:10.1116/1.587774

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Ballistic‐electron emission microscopy (BEEM), performed under ultrahigh vacuum conditions at the room‐temperature‐grown Au/n‐Si(111)7×7 interface, allows a measurement of the BEEM current for tip biases up to ≊ 8 V without a noticeable change in ballistic transmissivity. The differences of the present results to previous reports, where either no BEEM current was observed or the transmissivity was modified when applying high tip voltages, can be explained by the absence of intermixing at the Au/Si interface. Scanning tunneling microscope images of ≊40‐Å‐thick Au films reveal a characteristic topography of the metal surface with ≊2.5 Å high circular terraces stacked in up to four stages.

ISSN:1071-1023    

DOI:10.1116/1.587775

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Single Si atoms can be deposited onto a Si(111)‐7×7 sample surface from the tip of a scanning tunneling microscope, the Si atoms to be deposited being previously picked up by the tip from another place on the sample surface. The crystallographic position of these deposited Si atoms changes as their density increases. The deposited Si atoms can be re‐removed by picking them up again with the tip, the substrate atomic arrangement remaining unperturbed. It is also possible to fill Si atom vacancies on the sample surface with a Si atom deposited from the tip.

ISSN:1071-1023    

DOI:10.1116/1.587776

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

The atomic structure of α‐7×7 and γ‐phase structure has been investigated with use of scanning tunneling microscopy. Structural models for both phases are presented where both structures are based on the dimer adatom stacking‐fault structure. Continuously linked boundaries are observed between these phases, in contrast to those between α‐7×7 and √7×√7 phase. It is found that the properties of the boundaries are closely related to the basement structure. Phase transitions appearing at higher or lower temperature are discussed in terms of growth dynamics.  

ISSN:1071-1023    

DOI:10.1116/1.587777

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

The size and distribution of surface features of porous silicon layers have been investigated by scanning tunneling and atomic force microscopy. Pores and hillocks down to 1–2 nm size were observed, with their shape and distribution on the sample surface being influenced by crystallographic effects. The local density of electronic states show a strong increase above 2 eV, in agreement with recent theoretical predictions.

ISSN:1071-1023    

DOI:10.1116/1.587778

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Amorphous hydrogenated silicon (a‐Si:H) basedpn‐doping superlattices grown by radio‐frequency‐plasma deposition onto crystalline Si substrates were cleaved in air according to the crystallographic orientation of the substrate material. Their cross‐sectional face is investigated using scanning tunneling microscopy (STM) and scanning force microscopy (SFM). With constant current STM in a dry nitrogen ambient at atmospheric pressure tip deflections due to thepn‐superlattice periodicity are observed. With contact mode SFM in air only the transition from the substrate to the superlattice thin film but no periodic structure is resolved. A model calculation suggests that the apparent periodic height variation in constant current STM is due to a difference betweenp‐ andn‐type doped layers in their density of accessible states for tunneling.

ISSN:1071-1023    

DOI:10.1116/1.587779

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Images of grown‐in and deformation‐introduced dislocations penetrating cleaved {110} surfaces of ZnSe and ZnS were obtained by scanning force microscopy. No electrical effects associated with dislocations were found.

ISSN:1071-1023    

DOI:10.1116/1.587780

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Scanning force microscopy for studying ferroelectric domain structures is applied. The force microscope was operated in the contact static mode (repulsive force regime) and in the noncontact dynamic mode (attractive force regime). These two techniques were applied to study cleavage faces of ferroelectric crystals of GASH (guanidinium aluminum sulfate hexahydrate) and TGS (triglycine sulfate) crystals. Using the contact mode, the positive and negative domains are revealed by opposite contrast. In the dynamic noncontact mode, the domain walls are revealed. The experimental setup allowsinsituexperiments to study the dynamics of ferroelectric domains. First results on the time dependence of the domains motion in TGS will be presented.

ISSN:1071-1023    

DOI:10.1116/1.587781

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

The brittle fracture surfaces of Ti3Al+Nb and Ti3Al were investigated with a scanning tunneling microscope (STM) under ambient conditions using a mechanically cut platinum iridium alloy wire and electrochemically etched tungsten tips. The results show that the fracture surfaces consist of cleavage steps with dimensions of the order of ∼2 nm for Ti3Al+Nb and ∼60 nm for Ti3Al, similar to cleavage surfaces observed by scanning electron microscopy. Some cavities between the microcleavage steps on the scale of a few nanometers were observed for Ti3Al+Nb. The reproducibility of the STM images under ambient conditions depends on the applied bias voltage. The quality of the STM images obtained via tungsten tips is better.

ISSN:1071-1023    

DOI:10.1116/1.587782

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

The surface of iron meteorite consisting of FeNi–FeS has been studied with scanning tunneling microscope. Fairly good topographic maps for a large area (−3 μm) are obtained showing strong ridge structures with 200–700 nm in spacing, 100–400 nm in valley depth. The top of the ridges has also been observed in more detail. Structures like parallel ridges, promontorylike with faceted surfaces can be seen clearly, which possess some characters as in process of crystallite growth pattern on the earth.

ISSN:1071-1023    

DOI:10.1116/1.587783

出版商:American Vacuum Society    

年代:1994

数据来源: AIP