摘要:

Cyclotron resonance of the two‐dimensional hole gas (2DHG) in the strained‐layer quantum well structure of In0.20Ga0.80As/GaAs is observed in far‐infrared transmission measurements made at 4.2 K. The cyclotron mass of the 2DHG in the In0.20Ga0.80As channel is (0.191±0.008)mefor a 2D hole densityp2D=8.5×1011/cm2.

ISSN:0003-6951    

DOI:10.1063/1.101816

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The Wigner particle trajectories in phase space for double‐barrier semiconductor quantum well structures are investigated by numerically calculating the Wigner distribution function. The determination of the particle dynamics of the phase points allows for an estimation of tunneling times, particle currents, and particle energies associated with the statistics of bound and open trajectories across the double‐barrier structures.

ISSN:0003-6951    

DOI:10.1063/1.101817

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Conventional thermal annealing with various caps on the surface of the sample is used to selectively disorder one section of a multiple quantum well GaAs/AlGaAs structure. In the disordered section, the shift of the photoluminescence peak is in the range where the chirp parameter (ratio of real index change over absorption change) is large at the laser wavelength in the undisordered material. Moreover, photoconductivity measurements on samples under reverse bias, as well as laser testing, prove that the electric properties are preserved by the thermal treatment. Therefore, the investigated process should be highly suitable for the monolithic integration of a laser and phase modulator.

ISSN:0003-6951    

DOI:10.1063/1.101818

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

A transmission electron microscopy study of porous silicon reveals that pores selectively propagate in the ⟨100⟩ crystallographic directions on bothn‐ andp‐type silicon, independent of dopant concentration or anodization conditions.

ISSN:0003-6951    

DOI:10.1063/1.101819

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Carbon was implanted into GaAs at doses between 1013and 5×1014cm−2, either by itself or with Ga coimplantation at room temperature or 200 °C. Activation percentages as high as 40% were obtained for C+Ga implants at 5×1014cm−2compared to <3% for C implantation only. The peak activation occurs for an annealing temperature of 800 °C for 10 s, while above this the net activation decreases, apparently due to site switching. The C shows fairly minimal redistribution during anneals up to 1000 °C in contrast to other acceptor dopants in GaAs. The formation of highly resistive (>106&OHgr;/&laplac;) layers in C‐doped (p∼2×1020cm−3) GaAs is possible by using oxygen bombardment doses above 5×1014cm−2. Under these conditions the evolution of the implanted layer resistivity with annealing temperature can be described by the usual trap‐related compensation mechanism.

ISSN:0003-6951    

DOI:10.1063/1.101820

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We describe a novel method of confining carriers by deliberately creating large inhomogeneous strain patterns in a quantum well. The strain modulates the band gap to provide lateral quantum confinement for excitons. Here, we generate strain confinement in an InGaAs quantum well by reactive ion beam assisted etching through an overlying compressed pseudomorphic quaternary layer using etch masks patterned by electron beam lithography. Photoluminescence spectra of arrays of wires and dots show red‐shifted band gaps in direct evidence of lateral confinement. We compare our results to finite element calculations of the inhomogeneous strain in an InP substrate from a compressed overlayer patterned into rectangular wires.

ISSN:0003-6951    

DOI:10.1063/1.102266

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Passivation of threading dislocations in an incommensurate Ge0.36Si0.64/Si structure is studied using hydrogen plasma anneal. The reverse current ofpnjunction diodes made of the above structure is reduced by more than 30 times after hydrogenation. Associated improvements in the current‐voltage (I‐V) characteristics is also observed. Capacitance‐voltage (C‐V) measurements reveal that the shallow dopants neutralized by hydrogenation reactivate at lower temperatures than the passivated deep level defects. Secondary‐ion mass spectroscopy (SIMS) analysis established the depth of diffusion of hydrogen under the experimental conditions. Work in this direction could eventually lead to the integration of infrared detectors with Si very large scale integration (VLSI).

ISSN:0003-6951    

DOI:10.1063/1.101821

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The effects of background doping, surface encapsulation, and As4overpressure on carbon diffusion have been studied by annealing samples with 1000 A˚p‐type carbon doping spikes grown within 1 &mgr;m layers of undoped (n−), Se‐doped (n+), and Mg‐doped (p+) GaAs. The layers were grown by low‐pressure metalorganic chemical vapor deposition using CCl4as the carbon doping source. Two different As4overpressure conditions were investigated: (1) the equilibriumpAs4over GaAs (no excess As), and (2)pAs4∼2.5 atm. For each As4overpressure condition, both capless and Si3N4‐capped samples of then−‐,n+‐, andp+‐GaAs crystals were annealed simultaneously (825 °C, 24 h). Secondary‐ion mass spectroscopy was used to measure the atomic carbon depth profiles. The carbon diffusion coefficient is always low, but depends on the background doping, being highest in Mg‐doped (p+) GaAs and lowest in Se‐doped (n+) GaAs. The influence of surface encapsulation (Si3N4) andpAs4on carbon diffusion is minimal.

ISSN:0003-6951    

DOI:10.1063/1.101822

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Ordered structure in GaInP alloys grown on (001) GaAs substrates by low‐pressure metalorganic vapor phase epitaxy has been investigated by means of x‐ray diffraction and transmission electron microscopy. We found a broad peak of CuPt I type (111)Bordering in the x‐ray measurements. X‐ray results gave the total amount of ordered region and the average size of each ordered domain. Room‐temperature photoluminescence peak energy anomalies were found to be related to the amount of the order phase.

ISSN:0003-6951    

DOI:10.1063/1.101823

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Ge (111) was self‐implanted in ultrahigh vacuum to prepare an impurity‐free amorphous layer. The same extraordinary amorphous state of Ge was induced as that found earlier with121Sb+implantation in normal vacuum. This eliminates the possibility that this anomalousa‐Ge is impurity stabilized.

ISSN:0003-6951    

DOI:10.1063/1.101824

出版商:AIP    

年代:1989

数据来源: AIP