摘要:

The effects of free‐carrier broadening on luminescence linewidths in InGaAs‐InP quantum wells (QW’s) are demonstrated using Schottky barrier depletion and magnetic field quantization of the conduction‐band‐energy levels. After removal of free‐carrier broadening, linewidths of 5 meV for 100‐A˚, and 3.5 meV for 150‐A˚ QW’s grown by metalorganic chemical vapor deposition are obtained. Widths of 3.4 meV for a 110‐A˚ QW grown by molecular beam epitaxy (MBE) on ann+substrate, and only 2.0 meV at 6.2 T for a similar MBE sample grown on a semi‐insulating substrate are also reported.

ISSN:0003-6951    

DOI:10.1063/1.97675

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Single crystals of cubic SiC that are free of antiphase domains were successfully grown by chemical vapor deposition on Si substrates inclined at 2° from (100) towards (011). The relationship between the generation of antiphase domains and the inclination of a surface was investigated by using spherically polished Si substrates. Inclination, except towards (011), resulted in the generation of antiphase domains. Elimination of antiphase domains was confirmed by molten KOH etching of the grown layer.

ISSN:0003-6951    

DOI:10.1063/1.97676

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Chlorine‐enhanced GaAs maskless etching has been performed with a novel focused ion beam etching (FIBE) system. The system is composed of an air‐locked ultrahigh vacuum chamber, a 30‐keV Ga+FIB column, and a fine nozzle. The nozzle irradiates a high‐density Cl2flux on a desired, small area of the sample while retaining a sufficiently low surrounding gas pressure for stable Ga+FIB emission. Condensed Ga residues, appearing on the etched surface with no Cl2gas, could be suppressed under Cl2gas irradiation. Highly chemically enhanced sputtering yields (up to 50 GaAs molecules per incident ion) were obtained by selecting the optimum relationship between scanning time and Cl2gas pressure. At the maximum yield, a deep groove (about 6 &mgr;m) with a smooth surface was obtained by line‐scanning FIBE. The etching was applied to laser‐mirror formation of an AlGaAs laser. A vertical mirror facet, fabricated in advance by a reactive ion beam etching, was trimmed about one micron thick by line‐scanning FIBE. Light output versus current characteristics did not change before and after FIBE and the etching has been shown to be useful for laser‐mirror formation.

ISSN:0003-6951    

DOI:10.1063/1.97677

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The performance of thin‐film transistors fabricated in unrecrystallized (small‐grain) polcrystalline silicon is shown to be greatly improved by depositing the films at much lower pressures than normally used in the low‐pressure chemical vapor deposition process. Electronic measurements on completed devices are presented and related to the film structure by transmission electron microscopy examination.

ISSN:0003-6951    

DOI:10.1063/1.97678

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

We present an analytical theory of the experimentally observed enhanced impact ionization rate in multiquantum well structures, which is based on a modification of Schockley’s [Solid State Electron.2, 35 (1961)] lucky electron theory. The general expression always predicts an enhancement in the ionization rate over the corresponding bulk value. The model is compared to both Monte Carlo calculations and recent experimental results. It is concluded that owing to the nonlinear aspects of impact ionization, the ionization rate can be significantly enhanced by the superposition of a uniform electric field and any spatially periodic electric field.

ISSN:0003-6951    

DOI:10.1063/1.97679

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Silicon‐on‐insulator structures have been fabricated using implantation of 160 keV oxygen ions at a dose of 1.9×1018atoms/cm2with a wafer temperature of 500 °C and no oxide cap. Both the as‐implanted and annealed wafers were examined with optical reflectometry to determine the resultant interference pattern produced by the presence of the buried layer of SiO2. The optical data are compared to the predictions of a calculation which simulated the geometry using a detailed multilayer optical model. Parameters of the model were adjusted to provide a best fit to the data. The optical prediction closely matches data from destructive measurements. It is demonstrated that the redistribution of oxygen due to annealing can be monitored with this technique.

ISSN:0003-6951    

DOI:10.1063/1.97680

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Rapid thermal annealing with incoherent light was used to fabricate planar, Be‐implantedp‐njunctions in GaAs. Diodes of varying diameter were used to determine if the residual implant damage would cause the space‐charge recombination current to dominate the surface recombination current. Unpassivated diodes are dominated by surface recombination over the 20–150 &mgr;m range of diameters investigated. Passivation of diode structures with a surface layer of high‐resistivity Al0.4Ga0.6As grown by metalorganic chemical vapor deposition resulted in a significant reduction of surface recombination current and permitted the measurement of the space‐charge recombination current. The space‐charge recombination current for these diodes was found to be similar in value to that previously reported for Zn‐diffused GaAs junctions.

ISSN:0003-6951    

DOI:10.1063/1.97681

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The Si matrix phase of directionally solidified Si‐TaSi2composite structures has been characterized by deep level capacitance transient spectroscopy, using the grown‐in metal‐semiconductor junctions. The Si is found to be of high quality. No electrically active Ta was detected with a minimum experimental sensitivity of ∼6×1011cm−3. Some samples exhibited one of two defect states having electron emission activation energies of 0.36 and 0.65 eV. These states appear to be associated with dislocations.

ISSN:0003-6951    

DOI:10.1063/1.97682

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

Results on the specular beam intensity behavior in reflection high‐energy electron diffraciton during molecular beam epitaxial growth of Al0.3Ga0.7As on GaAs(100) are reported. The behavior of steady‐state intensity as a function of substrate temperature exhibits irreversible character. The results indicate that the Al reactivity with As and residual impurities is the dominant factor controlling the surface morphology and hence the nature of inverted interfaces. A critical need for choosing optimal growth conditions prior to initiation of Al0.3Ga0.7As growth thus emerges.

ISSN:0003-6951    

DOI:10.1063/1.97683

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The structures of Si near‐surface damage induced after the removal of a thick SiO2layer on Si using reactive ion etching with various etching gases were studied by transmission electron microscopy. Cross‐sectional micrographs showed the presence of a fluorocarbon film on the Si surface after the SiO2layer is etched away. No extended defects were observed in Si etched utilizing pure CF4or CF4/20% H2etching gas, even after a 25‐min overetch into Si. For a CF4/40% H2etching gas, no extended lattice defects were evident for overetch times of up to 5 min. However, extensive damage was found in the Si surface layer after a 10‐min or longer overetch. This extensive damage consists of {111} planar defects distributing underneath the Si surface to a depth of 300 A˚. The planar defects are highly decorated by impurities, likely H and possibly C, F. A pure H2etching gas was found to introduce a heavily damaged layer and a high density of extended defects near the Si surface after only a 5‐min overetch. These observations indicate that H ion bombardment plays an important role in the formation of Si near‐surface damage during reactive ion etching.

ISSN:0003-6951    

DOI:10.1063/1.97684

出版商:AIP    

年代:1987

数据来源: AIP