摘要:

A compensating deep donor with a binding energy of 57 meV in ZnSe:N epilayers has been studied by means of photoluminescence and selectively excited photoluminescence (SPL) spectroscopy. The emission of 2.766 eV due to transitions between the deep donors and free holes (DdF) was observed at 4 K under strong excitation conditions. The emission at 2.681 eV due to transitions between deep donors and nitrogen acceptors (DdAP) is attributed to the same deep donor as that of theDdFemission through a detailed SPL study. It is also demonstrated that the SPL technique is important for studying the deep levels in ZnSe:N. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115375

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We investigate the second order optical susceptibility &khgr;(2)of symmetric GaAs/AlGaAs quantum wells under applied bias, in the frequency region near half the band gap. The second harmonic is generated in a transmission geometry, and is separated from bulk contribution by a lock‐in detection technique. As opposed to previous reports, we find that &khgr;xzx(2)is much higher than &khgr;zxx(2). For 50 A˚ quantum wells, &khgr;xzx(2)≊25 pm/V and &khgr;zxx(2)≊0 at &lgr;=1.66 &mgr;m under an applied electric fieldE=50 kV/cm. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115376

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The effect of growth temperature, deposition rate, and substrate misorientation angle on size, density, and uniformity of InP islands grown on (100) GaAs by metalorganic vapor phase epitaxy is investigated. The density of InP islands is observed to remain constant as a function of growth temperature in the temperature range of 620–680 °C. Below 620 °C the island density increases with decreasing temperature. Above 605 °C a subset of islands having a uniform size is observed. The degree of uniformity depends largely on the deposition rate and the size of the uniform islands on the growth temperature. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115377

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Measures of the mosaic dispersion of a series of self‐nucleated AlxGa1−xN thin films, grown by low‐pressure metalorganic chemical vapor deposition in a nitrogen carrier gas, have been accumulated by a combination of reciprocal space x‐ray scattering patterns and real space images from scanning tunneling and atomic force microscopies. The films are shown to be dense mosaics of highly oriented islands whose in‐plane and out‐of‐plane orientational coherence and in‐plane island size decrease with increasingx. The highly correlated reductions in island size and orientational coherence are believed to be attributable to a decrease in surface mobility of reactants, which is independent of nucleation layer or carrier gas. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115378

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A molecular beam epitaxy growth monitoring method is developed for distributed Bragg reflectors and vertical‐cavity surface‐emitting laser (VCSEL) resonators. The wavelength of the substrate thermal emission that corresponds to the optical cavity resonant wavelength is selected by a monochromator and monitored during growth. This method allows VCSEL cavities of arbitrary design wavelength to be grown with a single control program. This letter also presents a theoretical model for the technique which is based on transmission matrices and simple thermal emission properties. Demonstrated reproducibility of the method is well within 0.1%. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115379

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Optical properties of scratched InP specimens were studied by means of cathodoluminescence (CL). A new luminescence band around 942 nm (S1) was detected in the vicinity of scratches. The S1 band is composed of two peaks at 938 and 946 nm. Monochromatic CL images showed that the S1 luminescence is constrained to regions of high residual strain and not related to dislocations or cracks. The S1 intensity increased in samples with a higher Fe content. S1 vanished after 450 K annealing. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115380

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The gain‐spontaneous recombination characteristics have been calculated for a 40 A˚ Zn0.8Cd0.2Se‐ZnSe quantum well including many body effects. We examine the effect of the inclusion of the Coulomb enhancement on the gain spectra and the gain‐current relationship. We show that, in the absence of the Coulomb enhancement, the threshold current density of a 340 &mgr;m 40 A˚ Zn0.8Cd0.2Se‐ZnSe quantum well laser is underestimated by approximately 40% and the lasing wavelength overestimated by 4 nm. Our calculation of the scattering lifetime for the first electron‐heavy hole transition gives a lifetime varying between 29 and 37 fs, and shows that the carrier‐phonon scattering mechanism in II‐VI quantum wells is more dominant than in III‐V materials. We also comment on the effect the neglect of Coulomb enhancement has on the calculation of leakage currents in a laser at threshold. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115381

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

In this letter we report on the observation of growth oscillations with monolayer periodicity by ellipsometry. An oscillation amplitude of &dgr;⟨&Vegr;1⟩=0.05 was measured using an optimized spectroscopicinsituellipsometer whose wavelength was tuned to the 2.65 eV resonance energy of the arsenic dimers covering the GaAs (001) growth surface. The monolayer periodicity was verified by parallel monitoring of the growth with reflectance anisotropy spectroscopy (RAS). ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.115382

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Hydrogenated amorphous silicon (a‐Si:H) films were prepared by remote plasma chemical vapor deposition (RPCVD) using SiH4/SiH2Cl2/He/H2mixtures. With increasing Cl content ina‐Si:H up to about 1019cm−3, the stablity of photoconductivity under light illumination was improved with keeping the defect density and Urbach energy constant. We deposited hydrogenated amorphous silicon films with hydrogen content of 6 at. %, Cl content of ∼1019cm−3, and defect density of 3×1015cm−3, which exhibited very small photoconductivity degradation under light illumination. The optimum Cl concentration ina‐Si:H for stablea‐Si:H appears to be ∼1019 cm−3. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115383

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Breakdown voltages of InP/InGaAs avalanche photodiodes have been analyzed with structure parameters, such as multiplication layer width (MLW) and absorption layer thickness. It is shown that there exists a critical MLW,w0, where the breakdown voltage is the lowest. As MLW increases, the breakdown voltage increases slowly in the region of MLW≥w0while the breakdown voltage decreases in the region of MLW≤w0. It is also revealed thatw0is a function of absorption layer thickness. The measured breakdown voltages having MLWs of 0.15–0.4 &mgr;m were reported and compared to the calculated ones, which agreed very well with each other. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115384

出版商:AIP    

年代:1995

数据来源: AIP