摘要:

Si/SiO2interface structures in laser‐recrystallized Si on SiO2were studied with a high‐resolution transmission electron microscope. The (001) Si/SiO2interface with (001) Si substrate as a seed was excellent in flatness, flatter than that of the initial interface before recrystallization. However, the (11¯5) Si/SiO2interface with (11¯5) Si substrate was saw‐toothed with {100}Tand {111}Tmicrofacets. After twin boundary generation, the interface was changed to {110}Tor {111}Tand was flattened considerably. A Si/SiO2interface reaction occurred during laser recrystallization. Since low‐index Si planes are thought to have low interface energies with SiO2at their interface, atomically flat or saw‐toothed interfaces appeared as a result of this interface reaction. Moreover, twin boundaries, rather than saw‐toothed interfaces, might have been generated for the reduction of the interface energy.

ISSN:0003-6951    

DOI:10.1063/1.102433

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A technique has been developed to grow (111) textured diamond films on smooth substrates using attached diamond seeds. The degree of texture is defined by the initial texture of the seeds. This initial texture depends upon the seed size and the cleaning procedure. Under the best conditions, over 90% of the seeds exhibit a (111) texture with a tip angle of less than 0.25°. Further growth of diamond on these seeds does not affect the texture, and diamond films obtained by such growth are expected to have smoother surfaces and more controlled doping than nontextured polycrystalline films.

ISSN:0003-6951    

DOI:10.1063/1.101830

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Room‐temperature photoconductivity measurements were carried out on metalorganic chemical vapor deposition grown CdTe‐ZnTe superlattices with a periodicity of 30–80 A˚. The threshold of the photoconductivity measurements varied with the size of the well. Transition of the electron to then=1 level in the conduction band was observed in all samples; the transition to then=2 level was found for the superlattices with well width exceeding 25 A˚. These findings agree very well with room‐temperature absorption measurements performed on the same superlattices and with model calculations which were based on the Kronig–Penney model with Bastard’s boundary conditions.

ISSN:0003-6951    

DOI:10.1063/1.101831

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A double‐heteroepitaxial Si/&ggr;‐Al2O3/Si structure was realized. An epitaxial (100)Si layer with high quality was successfully grown on a (100)&ggr;‐Al2O3/(100)Si substrate by Si2H6gas‐source molecular beam epitaxy at substrate temperatures between 700 and 800 °C. The &ggr;‐Al2O3/Si substrate was fabricated by low‐pressure chemical vapor deposition with Al(CH3)3and N2O gases. The reflection high‐energy electron diffraction patterns of the 3000‐A˚‐thick Si epitaxial layer indicated streaked 2×1 patterns. This Si film had a mirror‐like surface, and smooth surface morphology was observed from replica electron micrographs. From the Auger depth profile of the epitaxial layers, it was found that the double‐heteroepitaxial Si/Al2O3/Si structure had a sharper interface between Al2O3and the epitaxial Si film due to the low growth temperatures.

ISSN:0003-6951    

DOI:10.1063/1.102434

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We discuss optical data obtained on (InAs/GaAs)‐InGaAlAs multiquantum well structures grown by molecular beam epitaxy. The combined use of photoluminescence and photoluminescence excitation to study such structures is an efficient test of the quality of the highly strained InAs/GaAs ordered alloy, which is used as the well material. The electron effective mass and the lifting of the valence‐band degeneracy in InAs/GaAs short‐period superlattices are obtained experimentally for the first time.

ISSN:0003-6951    

DOI:10.1063/1.101832

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Native silicon (Si) oxide growth on Si (100) wafers in air and in ultrapure water at room temperature requires coexistence of water and oxygen in the air and ultrapure water ambients. The growth rate data onn‐,n+‐, andp+‐Si (100) in air indicate layer‐by‐layer growth of an oxide. The growth rate onn‐Si (100) in ultrapure water may be governed by a parabolic law. For native oxide growth in ultrapure water, the number of Si atoms dissolved in ultrapure water is over one order of magnitude larger than the number of Si atoms contained in the grown native oxide film. The structural difference between the native oxide film in air and in ultrapure water is also discussed.

ISSN:0003-6951    

DOI:10.1063/1.102435

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The formation of discrete layers of dislocation loops near the projected ion ranges (Rploops) of 65–80 keV, high‐dose (5×1015–2×1016/cm2) P+‐implanted (001)Si was observed by cross‐sectional transmission electron microscopy (XTEM). Both the energy and dose dependence of the annealing behaviors ofRploops provided strong evidences that they are related to P clustering. The inactivation of dopants due to precipitation, hence the appearance ofRploops, is correlated to the sheet resistance data. The retardation of the solid phase epitaxial growth was shown to be related to the formation ofRploops. UsingRploops as an indicator of changes in point‐defect distribution, a combined XTEM and plan‐view TEM study was found to be most appropriate for the study of the precipitation process in high‐dose P+‐implanted silicon.

ISSN:0003-6951    

DOI:10.1063/1.101833

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Ion‐implanted In0.1Ga0.9As metal‐semiconductor field‐effect transistors (MESFETs) have been fabricated on 3 in. GaAs (100) substrates. The structure comprises an undoped InGaAs epitaxially layer grown directly on a GaAs (100) substrate by the metalorganic chemical vapor deposition (MOCVD) technique. Si+28is ion implanted into the InGaAs layer to form an active channel layer. MESFETs with 100 &mgr;m gate width and 0.5 &mgr;m gate length are fabricated using standard process techniques. The best device shows a maximum transconductance of 426 mS/mm. FromS‐parameter measurements, the current‐gain cutoff frequencyftis 37 GHz and the maximum available gain cutoff frequencyfmaxis 85 GHz. These results are comparable to InGaAs MESFETs grown by MBE.

ISSN:0003-6951    

DOI:10.1063/1.101834

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Employing a GaSb/GaAs strained‐layer superlattice and a GaSb cap, specific contact resistivities as low as 3.2×10−7&OHgr; cm2have been realized for nonalloyed ohmic contact top‐type GaAs. This contact structure is shown to give low contact resistances irrespective of the contact metals, including AuBe, AuGe/Ni/Au, and Au. Excellent thermal stability for AuBe contacts was obtained when sintered.

ISSN:0003-6951    

DOI:10.1063/1.101835

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

AlAs‐GaAs‐AlAs double‐barrier resonant tunneling diodes (DBRTDs) with different doping levels in the AlAs layers have been investigated. Two‐step spacer layers were used in all samples. Peak‐to‐valley current ratios (PVCRs) as high as 3.5 (11.3), 3.5 (11.3), and 2.7 (8.2) were observed at 300 K (77 K) for samples with undoped, 1.2×1017cm−3, and 3×1018cm−3doped AlAs barriers, respectively. These results indicate that resonant tunneling is not strongly affected by ionized Si atoms in the AlAs barriers. The excellent PVCRs observed in DBRTDs with two‐step spacer layers is not because of low background impurity densities in the active region, but because of a third barrier formed by band bending in the spacer layers.

ISSN:0003-6951    

DOI:10.1063/1.101836

出版商:AIP    

年代:1989

数据来源: AIP