摘要:

Mixed monolayers of 5‐(4‐N‐decylpyridinium)‐10,15,20‐tri‐p‐tolyl porphyrin (PyP) and arachidic acid (AA) were prepared on a water surface as a precursor for organized arrays of photodiodes. By compression and expansion of the films, PyP self‐assembled to form nearly circular domains with their size dependent on the molar ratio of PyP and AA. These structures were successfully incorporated into Schottky‐type cells, and their photoelectric properties were studied on the domain level by illumination of a focused light with a diameter of 20 &mgr;m. The short‐circuit photocurrents showed large fluctuations depending on the position of illumination, which reveals that the PyP domains function as photodiode arrays.

ISSN:0003-6951    

DOI:10.1063/1.104877

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The effect of Ar laser irradiation upon ZnTe homoepitaxial growth has been investigated in low‐pressure metalorganic vapor phase epitaxy. Dimethylzinc and diethyltelluride were used as source materials. The growth rate of the ZnTe layer was greatly enhanced by irradiating vertically onto the (100) substrate. Photoluminescence measurements revealed that the quality of the layer is improved by the irradiation. Diethyltelluride is effectively decomposed on the surface by the irradiation.

ISSN:0003-6951    

DOI:10.1063/1.104878

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report on a new passivation procedure of the GaAs surface based on a thermal treatment under a PH3overpressure. This treatment results, by As/P exchange, in the formation of a thin superficial GaP layer which prevents the formation of an arsenic oxide, as observed by x‐ray photoelectron spectroscopy analysis. Subsequent increase of the photoluminescence signal indicates improved electronic properties of GaAs surfaces as a result of this passivation procedure.

ISSN:0003-6951    

DOI:10.1063/1.104879

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Data are presented on a high‐performance native‐oxide coupled‐stripe AlyGa1−yAs‐GaAs‐InxGa1−xAs quantum well heterostructure laser realized by the recently introduced simple process of ‘‘wet’’ oxidation (H2O vapor+N2,≳400 °C, 3 h) of the upper AlyGa1−yAs confining layer. If the native oxide between active stripes (ten 5 &mgr;m stripes on 10 &mgr;m centers) is brought into closer proximity with the waveguide and quantum well region (i.e., from 0.53 to 0.4 &mgr;m), the 10‐stripe laser operates decoupled because of increased (coupling) absorption losses and some index guiding.

ISSN:0003-6951    

DOI:10.1063/1.104880

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We discuss the electron tunneling time observed in a new AlGaAs/GaAs superlattice structure, the tunneling bi‐quantum well (TBQ). To calculate the nonresonant tunneling time, we made experiments on resonant tunneling to confirm that the 60% rule of conduction‐band discontinuity accurately evaluates the free tunneling probability of electrons. We found that the observed recovery time agrees quite well with the calculated longitudinal optical phonon emission tunneling time for thin (≤ 10 monolayers) barriers.

ISSN:0003-6951    

DOI:10.1063/1.104881

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We report here the successful fabrication of a planar, low dark current, and high sensitivity In0.4Ga0.6Asp‐i‐nphotodiode fabricated on a semi‐insulating GaAs substrate with the aid of a multistage strain‐relief buffer system. Without using surface passivation and anti‐reflection coatings, the detector has a quantum efficiency of 42% and a peak responsivity of 0.45 A/W at 1.3 &mgr;m wavelength. The reverse leakage current for the mesa‐etched photodiode with an active area of 2×10−4cm2is 5×10−9A at −5 V, and the breakdown voltage exceeds 25 V.

ISSN:0003-6951    

DOI:10.1063/1.104882

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The effect of extrinsic background doping on the transient enhancement of dopant diffusion for an ion‐implanted dopant is investigated to gain insight into the role of point defect charge states. The transient effect is found to be greatly increased for extrinsic background doping of the same type as the implanted ion, and reduced for background doping of the opposite type. Analysis of the relative enhancements for boron and phosphorous allows the position of the donor and acceptor levels for the silicon self‐interstitial to be extracted. The results are in good agreement with earlier work based on extrinsic oxidation‐enhanced diffusion.

ISSN:0003-6951    

DOI:10.1063/1.104883

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We demonstrate the novel application of the scanning tunneling microscope to find and probe the electronic transport properties of single semiconductor nanostructures at temperatures from room temperature to as low as 1.5 K. The current‐voltage characteristics of InGaAs/InAlAs resonant tunneling nanostructures clearly show negative differential resistance. From the dependence of the current on cross‐sectional area the lateral depletion is estimated to be 300 A˚.

ISSN:0003-6951    

DOI:10.1063/1.104884

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Hydrogenation effects on electrical and optical properties in GaAs epilayers grown on Si substrate by metalorganic chemical vapor deposition have been investigated. In as‐grown GaAs layers on Si substrates, typically four deep levels at 0.81, 0.68, 0.57, and 0.53 eV below the conduction band were observed by deep level transient spectroscopy. After hydrogen plasma exposure at 250 °C for 2.5 h, the 0.68 eV level disappeared. In addition, the reverse leakage current in the hydrogenated sample decreased by three orders of magnitude compared to the untreated sample. These effects persist after dehydrogenation process with a 5 min, 400 °C anneal. The results indicate that the hydrogenation for GaAs‐on‐Si has some benefits to its device application.

ISSN:0003-6951    

DOI:10.1063/1.104885

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

In this letter we report the first observation of enhanced electron mobility in GaN/AlxGa1−xN heterojunctions. These structures were deposited on basal plane sapphire using low‐pressure metalorganic chemical vapor deposition. The electron mobility of a single heterojunction composed of 500 A˚ of Al0.09Ga0.91N deposited onto 0.3 &mgr;m of GaN was around 620 cm2/V s at room temperature as compared to 56 cm2/V s for bulk GaN of the same thickness deposited under identical conditions. The mobility for the single heterojunction increased to a value of 1600 cm2/V s at 77 K whereas the mobility of the 0.3 &mgr;m GaN layer alone peaked at 62 cm2/V s at 180 K and decreased to 19 cm2/V s at 77 K. A 18‐layer multiple heterojunction structure displayed a peak mobility of 1980 cm2/V s at 77 K.

ISSN:0003-6951    

DOI:10.1063/1.104886

出版商:AIP    

年代:1991

数据来源: AIP