摘要:

Using time‐resolved photoluminescence, we have examined the optoelectronic properties of Ga0.5In0.5P/GaAs/Ga0.5In0.5P double heterostructures grown by organometallic chemical vapor deposition. For comparison, similar structures using Al0.4Ga0.6As/GaAs and Al0.5In0.5P/GaAs lattice‐matched heterointerfaces were also examined. For the Ga0.5In0.5P/GaAs heterostructure, we show that the recombination velocity at a Ga0.5In0.5P/GaAs interface can be less than 1.5 cm/s. As a result, photoluminescence decay times as long as 14 &mgr;s have been observed in undoped GaAs double heterostructures. This photoluminescence decay time varies with temperature asT1.59, characteristic of radiative recombination not limited by surface or bulk nonradiative recombination processes. For the Al0.4Ga0.6As/GaAs and Al0.5In0.5P/GaAs heterostructures examined in this study, the upper limits of the interface recombination velocity were 210 and 900 cm/s, respectively.

ISSN:0003-6951    

DOI:10.1063/1.101656

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

When AlAs/GaAs layer samples are subjected to Ar+ion bombardment at liquid‐nitrogen temperature, it is shown that very different damage structures are produced in the two materials. While the GaAs is relatively easily amorphized, the AlAs is quite resistant to damage accumulation and remains crystalline for the ion doses employed in these investigations. Epitaxial regrowth of buried amorphous GaAs layers of thicknesses up to 150 nm can be induced by rapid thermal annealing. It is demonstrated that differences in the initial damage state have a strong influence upon the nature of lattice defects produced by annealing.

ISSN:0003-6951    

DOI:10.1063/1.101657

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Transport properties of electrons in a novel in‐plane superlattice structure are studied and the field‐effect transistor action has been demonstrated. The structure consists of ann‐AlGaAs/GaAs modulation‐doped heterojunction in which an array of monolayer‐thick AlAs grid is embedded with an average period of 162 A˚ in the channel region of the heterojunction. This grid has been prepared with molecular beam epitaxy by depositing a half monolayer of AlAs on a GaAs (001) vicinal plane, where periodically spaced atomic terraces are formed. The electron mobilities &mgr;∥,&mgr;⊥parallel and normal to the grid are measured as functions of electron concentrationNS. While the mobility ratio (&mgr;∥/&mgr;⊥) is nearly unity at lowNS, the ratio is found to get as large as 2.2 asNSincreases. This anisotropic behavior of &mgr; is well accounted for by the calculated nonparabolicity in the miniband structure of in‐plane superlattices.

ISSN:0003-6951    

DOI:10.1063/1.101658

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We report the successful growth of ZnTe on nearly lattice‐matched III‐V buffer layers of InAs (0.75%), GaSb (0.15%), and on GaAs and ZnTe by molecular beam epitaxy.Insitureflection high‐energy electron diffraction measurements showed the characteristic streak patterns indicative of two‐dimensional growth. Photoluminescence measurements on these films show strong and sharp features near the band edge with no detectable luminescence at longer wavelengths. The integrated photoluminescence intensity from the ZnTe layers increased with better lattice match to the buffer layer. The ZnTe epilayers grown on high‐purity ZnTe substrates exhibited stronger luminescence than the substrates. We observe narrow luminescence linewidths (full width at half maximum ≊1–2 A˚) indicative of uniform high quality growth. Secondary‐ion mass spectroscopy and electron microprobe measurements, however, reveal substantial outdiffusion of Ga and In for growths on the III‐V buffer layers.

ISSN:0003-6951    

DOI:10.1063/1.101659

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

The low‐temperature near‐band‐edge photoluminescence of thick (d≊36 &mgr;m) (100)CdTe epilayers grown on (100)GaAs substrates is investigated. Besides a dominating bound exciton emission, evidence for free‐exciton emission (n=1 and 2) and two electron transitions (TETs) of donor‐bound excitons is found. The defect involved in the TET is most likely a gallium‐related donor. This is concluded from the TET line wavelength adopting recent bulk CdTe TET data. A new emission line at 781.4 nm (1586.7 meV) is observed. It is tentatively assigned to a TET of a free exciton.

ISSN:0003-6951    

DOI:10.1063/1.101660

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We investigate theoretically three double‐heterojunction modulation‐doped field‐effect transistor structures with different channel composition. All of these transistors have an InxGa1−xAs channel sandwiched between two doped Al0.3Ga0.7As barriers with undoped spacer layers. In one of the structures,xvaries from 0 from either heterojunction to 0.15 at the center of the channel quadratically and in the other two, constant values ofxof 0 and 0.15 are used. We solve Poisson’s and Schro¨dinger’s equations self‐consistently for the electron wave function for all three cases. The results showed that the two‐dimensional electron gas (2DEG) concentration in the channel of the quadratically graded structure is higher than thex=0 one and slightly lower than thex=0.15 one, and the mean distance of the 2DEG is closer to the center of the channel for this transistor than the other two. These two effects have important implications on the electron mobility in the channel.

ISSN:0003-6951    

DOI:10.1063/1.101661

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Thermionic emission rates are reported for electrons in GaAs epilayers, where electrostatic barriers within the layers and GaAs/AlAs heterojunctions form different sides of the potential well. Attempt times at the two barrier types were observed to differ by factors above 107due to differing constraints on momentum conservation during emission. These emissions represent escape mechanisms for charge stored in a closed geometry, III‐V compound floating gate transistor, with potential application as dynamic random access or nonvolatile memories.

ISSN:0003-6951    

DOI:10.1063/1.101662

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

We show that the concentration of boron at the interface between a silicon epitaxial layer and ann‐type Si substrate can be reduced to 109–1010atoms cm−2, near the detection limit of secondary‐ion mass spectrometry, when passivating oxide is desorbed from the substrate surface in a hydrogen ambient. Interfacial boron contamination is found to be much higher when the substrate surface oxide is desorbed in ultrahigh vacuum prior to growth, consistent with previous studies of Si molecular beam epitaxy. The hydrogen ambient is effective in removing boron only during the decomposition of the surface oxide.

ISSN:0003-6951    

DOI:10.1063/1.101663

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Voltage filling pulse measurements taken ona‐Si:H/c‐Si heterostructure Schottky diode samples are used to examine the capture of electrons from thec‐Si substrate intoa‐Si:H defect states. These measurements, along with the capacitance versus temperature spectra of these diodes, indicate a nearly zero conduction‐band offset (50±50 meV). In addition, we have observed trapping of holes at the valence‐band discontinuity &Dgr;Ev. A clear threshold for the subsequent optical release of these holes yields a value of &Dgr;Ev=0.58±0.02 eV. Our measurements also provide the energy and spatial distribution of deep defects within thea‐Si:H layer and indicate a region of anomalously large defect density (1018cm−3) within roughly 350 A˚ of thea‐Si:H/c‐Si interface.

ISSN:0003-6951    

DOI:10.1063/1.101664

出版商:AIP    

年代:1989

数据来源: AIP

摘要:

Photoluminescence in ZnSe/GaAs/Al0.4Ga0.6As single quantum well heterostructures is reported for the first time. These structures are grown by migration‐enhanced epitaxy, resulting in flat and abrupt ZnSe/GaAs heterointerfaces. The quantum size effect is clearly observed. Photoluminescence intensities of ZnSe/GaAs/Al0.4Ga0.6As single quantum well structures are comparable to those of Al0.4Ga0.6As/GaAs/Al0.4Ga0.6As, indicating a reasonable quality of the ZnSe layer as well as the ZnSe/GaAs heterojunctions. From the GaAs well width dependence of photoluminescence wavelength, the conduction‐ and valence‐band‐edge discontinuities are estimated to be 0.03–0.05 eV and 1.21–1.23 eV, respectively.

ISSN:0003-6951    

DOI:10.1063/1.101665

出版商:AIP    

年代:1989

数据来源: AIP