摘要:

We report the first two‐dimensional vertical‐cavity surface‐emitting laser (VCSEL) array with each laser emitting a unique, nonredundant wavelength. This was achieved by implementing spatially chirped layers in the VCSEL structure and obliquely aligning the array axes to the direction of the thickness chirp. We obtained 77 wavelengths from a 7×11 VCSEL array with all the lasers emitting single mode. Uniform wavelength separation between neighboring lasers is achieved with the direction of increasing wavelength rastering through the array. All the lasers exhibit nearly the same optical and electrical properties, in spite of the intentionally implemented difference in the emission wavelengths.

ISSN:0003-6951    

DOI:10.1063/1.104428

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Phase‐matching temperatures for 90° phase matching of Nd:YAG laser light have been measured in LiNbO3crystals with different Li/Nb ratios. Their melt and solid composition had been determined chemically with an accuracy of about 0.2%. Our results contrast to earlier work, no linear dependence of the phase‐matching temperature versus the Li/Nb ratio was found. The measured dependence shows that the phase‐matching temperature can be used as an excellent probe for the composition of LiNbO3.

ISSN:0003-6951    

DOI:10.1063/1.105216

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Epitaxial thin films of lead titanate(PbTiO3) and lanthanium‐modified lead titanate [(Pb, La)TiO3] have been successfully grown on (0001) sapphire substrates for the first time by the recently developed multi‐ion‐beam reactive cosputtering (MIBRECS) technique. The deposition processes and the thin‐film analyses studied by x‐ray diffraction (XRD), electron probe x‐ray microanalyzer (EPMA), and reflection high‐energy electron diffraction (RHEED) are reported. The experiments show that the multi‐ion‐beam reactive cosputtering process is very suitable for deposition of multicomponent oxide thin films with high reproducibility.

ISSN:0003-6951    

DOI:10.1063/1.104429

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The effect of silicon nitride (SiN) deposition on hydrogenated amorphous silicon (a‐Si:H) has been investigated to find the origin of the difference ofa‐Si:H/SiN interface properties caused by the order of deposition. Sheet conductance of the on‐state in inverted staggered (a‐Si:H on SiN) thin‐film transistors (TFTs) increases gradually with the substrate temperature (Tsub) of SiN, but decreases rapidly with theTsubof SiN in staggered TFTs (SiN ona‐Si:H). Photoluminescence experiments indicated that the degradation in staggered TFTs was due to the creation of defects ina‐Si:H by the deposition of the SiN overlayer. It was shown by Fourier transform infrared attenuated total reflection that the origin of the defects was hydrogen effusion froma‐Si:H.

ISSN:0003-6951    

DOI:10.1063/1.104430

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Electromigration properties in a single crystalline submicron width aluminum interconnection formed on Si(111) have been examined by resistance change measurements andinsituobservations using scanning electron microscopy. It was observed that single crystalline aluminum has an extremely high resistance to electromigration‐induced open circuit failures, when compared to polycrystalline copper and aluminum. The mechanism for the high resistance is considered to be a large activation energy, resulting from lattice diffusion. A tendency for void formation to become parallel to the longitudinal direction of the interconnection assisted the life time prolongation.

ISSN:0003-6951    

DOI:10.1063/1.104431

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The formation of amorphous interlayers (a‐interlayers) in ultrahigh‐vacuum‐deposited polycrystalline Nb and Ta thin films on (111)Si has been studied by cross‐sectional transmission electron microscopy. The growth ofainterlayers was found to follow a linear growth law initially in samples annealed at 450–500 °C and 550–625 °C for Nb/Si and Ta/Si, respectively. The growth then slows down and deviates from a linear growth behavior as a critical thickness of theainterlayer was reached. Theainterlayer/crystalline Si interface was found to be rather smooth. The roughness of the interface between the Nb layer andainterlayer was observed to decrease with annealing temperature and time. The observation suggested that the growth of theainterlayer was interface reaction controlled initially.

ISSN:0003-6951    

DOI:10.1063/1.104438

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Velocities of &agr;, &bgr;, and screw dislocations in InP crystals generated from surface scratches were measured as a function of stress and temperature by means of the etch pit technique. Effects of Zn and S impurities, acting as acceptor and donor, respectively, on the dislocation velocity were also investigated. lt was found that Zn impurity strongly retards the motion of all types of dislocations. On the other hand, S impurity is found to reduce the mobilities of &bgr; and screw dislocations while it enhances the mobility of &agr; dislocations.

ISSN:0003-6951    

DOI:10.1063/1.104439

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Development of a metal/organic‐semiconductor Schottky junction as an alternative to the metal/inorganic‐semiconductor junction is reported. Metal/polypyrrole (PP) junctions have been prepared with electrochemically deposited doped PP films of different thickness and various metals (In, Sn, Ti, and Al) as electrodes. The electrical characteristics of the junction depend upon the work functions of PP and the metal. It has been possible to prepare Schottky barriers on the PP films with a metal electrode having a work function lower than that of the polymer. Various physical characteristics of the polymer, work function, Fermi level, and carrier concentration have been estimated.

ISSN:0003-6951    

DOI:10.1063/1.104441

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We demonstrate layer disordering of ZnSe/ZnS strained‐layer superlattices (SLSs) induced by low‐damage N+or Li+ion implantation and low‐temperature annealing. The interdiffusion of Se and S atoms was observed by secondary‐ion mass spectrometry analyses. By reflectance measurements, a significant decrease in the refractive index, which is useful for waveguiding applications, was measured in the disordered SLS. In photoluminescence (PL) spectra, strong excitonic emission around 400 nm was observed in the disordered SLS corresponding to a damage recovery. A slight red shift of the PL peak observed in the early stages of annealing is interpreted as the relaxation of misfit strain by interdiffusion. For longer annealing times, the PL peak for an implanted SLS shifted towards the higher energy side, which clearly indicates layer disordering of the SLSs. This low‐temperature planar process will be very useful for the fabrication of II‐VI semiconductor optoelectronic devices.

ISSN:0003-6951    

DOI:10.1063/1.104442

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Polytype‐controlled crystal growth of SiC was carried out by using a sublimation method. Production yields as high as 80% and 85% for 4H and 6H single crystals were obtained, respectively. We observed in x‐ray diffraction pattern of SiC that space‐group‐forbidden peaks appear periodically among (000l) peaks. Their intensity is strong enough to be distinguished. These peaks represent the periodicity along thecaxis of each polytypic modification of SiC. X‐ray diffractometry using these peaks is quite useful and easy for a clear identification of the SiC polytypes.

ISSN:0003-6951    

DOI:10.1063/1.104443

出版商:AIP    

年代:1991

数据来源: AIP