摘要:

Bifacial solar cells are a promising possibility to lower the costs of solar electricity compared to conventional monofacial solar cells. These devices utilize the sunlight more efficiently since they are able to convert light incident on both sides of the cell. In this letter, a novel, cost-effective bifacial silicon solar cell structure is presented. On float-zone silicon, the cells exhibit conversion efficiencies of 19.4&percent; and 16.5&percent; under 1-sun front and rear illumination, respectively. Furthermore, a “symmetrical” version of the cells is presented demonstrating front and rear efficiencies of 18.4&percent; and 18.1&percent;. In spite of the simplicity of the cell fabrication process, these are the highest independently confirmed efficiencies ever reported for bifacial silicon solar cells. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118466

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Electron-beam-induced current (EBIC) profiles ofMo/CuInX2/CdS/ZnOthin film solar cells with X=Se, S were recorded at different temperatures. We measure the collection efficiency of cells as a function of the beam energy and subsequently identify the depth dependent collection function. For aCuInS2based cell, charge collection is maintained by diffusion transport of minority carriers to the junction with an effective diffusion length of 1.3±0.2 &mgr;m. This value is independent on temperature between 123 and 373 K. ACuInSe2based cell exhibits increased collection of charge carriers created at the back contact on decreasing temperature. The temperature variation of the EBIC profiles is discussed considering the effect of bulk and grain boundary recombination. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118467

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We investigated the low temperature(T<2K) photoluminescence (LTPL) emission of 6H–SiC samples after implantation of either boron or boron together with hydrogen. After implantation of boron and annealing at1700 °C, we detected new LTPL emission at 4205 Å. After implantation of hydrogen into the boron-implanted and annealed sample, another LTPL emission at 4183 Å appeared. We interpret two additional peaks as vibrational modes of the 4183 Å emission with energies of 86 and 118 meV. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118468

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The electronic quality of multicrystalline material produced by directional solidification has been evaluated by means of photoconductance techniques. Very high minority carrier lifetimes, in the vicinity of 200 &mgr;s, have been measured inp-type 1.5 &OHgr; cm material that had received a phosphorus diffusion gettering treatment. The measurements correspond to an effective lifetime averaged over an area of 3 cm2that includes several grain boundaries and reflects the combined bulk, grain boundary and surface recombination mechanisms. The high lifetime (15&mgr;s) also obtained in low resistivity 0.2 &OHgr; cm wafers has allowed the fabrication of solar cells with an open-circuit voltage of 657 mV (AM1.5 G, 100 mW/cm2, 25 °C), probably the highest ever reported for multicrystalline silicon. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118469

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

X-ray diffraction studies on nanometer sized lead sulfide particles reveal the presence of a compressive strain. A number of samples with particle sizes ranging from 2 to 16 nm were synthesized using the three dimensional periodic, bicontinuous cubic phase as a matrix. Samples of the larger size particles could be indexed to an fcc lattice. As the particle size decreased below 6 nm, a tetragonal distortion of the cubic lattice was observed, accompanied by a decrease in the unit cell volume. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118470

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Polar (100) surfaces of commercial CdTe and Cd(Zn)Te single crystals were prepared by ion sputtering and annealing at different temperatures and under Te flux, Cd flux, or in ultrahigh vacuum. Various surface reconstructions with high structural order were obtained. Soft x-ray photoemission investigations of the Cd and Te 3d surface core-level shifts were employed to derive the surface termination, revealing Cd-terminated surfaces for most preparations and various reconstructions. The results suggest that sputter/annealing cycles are suitable for the preparation of highly ordered and uniformly terminated substrates for semiconductor heterojunctions on CdTe and Cd(Zn)Te without the need of an additional buffer layer. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118432

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

The 4×1 (respectively 1×1) (001) GaN surfaces obtained when molecular-beam-epitaxy (MBE) growth is carried out on (001) cubic SiC were exposed to an As background pressure in the MBE chamber: The reconstructions rapidly and irreversibly changed to 2×2 [respectivelyc(2×2)] as usually observed for GaN growth on (001) GaAs. The usual reversible 2×2/c(2×2) transitions were consequently observed when bringing the Ga flux up or down. The respective positions for the 4×1/1×1 and 2×2/c(2×2) transitions were worked out as a function of the growth parameters. These observations indicate that the 2×2 andc(2×2) GaN surface reconstructions are mediated by As atoms which we tentatively assign to a surfactant effect. A simple structural model involving As dimers is proposed that accounts for Ga coverages of 0.5 and 1 monolayer for the 2×2 andc(2×2) growth regimes, respectively. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118433

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

We have successfully nickel doped a boron carbide (B5C) alloy film. The nickel doped boron-carbide (Ni-B5C1+&dgr;)thin films were fabricated from a single source carborane cage molecule and nickelocene [Ni(C5H5)2] using plasma enhanced chemical vapor deposition. Nickel doping transforms the highly resistive undoped film from ap-type material to ann-type material. This has been verified from the characteristics of diodes constructed of Ni-B5C1+&dgr;on bothn-type silicon andp-type B5C. The homojunction diodes exhibit excellent rectifying properties over a wide range of temperatures. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118434

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Free-standing wire arrays prepared by holographic exposure and wet chemical deep etching on a vertically arrangedGaAs/GaInAs/GaAs[001]single quantum well structure were characterized by x-ray grazing incidence diffraction using synchrotron radiation. Using a grazing angle of&agr;i≈0.05°the diffracted intensity stems primarily from the surface grating. It’s periodicity(D≈480 nm)was determined close to the(−220)and(220)Bragg reflection being parallel and perpendicular to the orientation of wires, respectively. The average wire width [(21.6±1.5) nmand(96.6±1.5) nm, respectively] and the coherence length of the grating(&xgr;≈2 &mgr;m)were obtained via Fourier transformation of the(220)shape function. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118473

出版商:AIP    

年代:1997

数据来源: AIP

摘要:

Studies of the transport critical current(Ic),magnetization, magnetic flux penetration, and microstructure of pressed and rolled Ag-clad(Bi,Pb)2Sr2Ca2Cu3Oxtapes (2223) have been made as a function of bending strain. Pressed tapes exhibited markedly less degradation ofIcfrom strain than did rolled tapes, while the magnetization of pressed tapes declined much more rapidly with bending strain than did either of the transport currents. Magneto-optical imaging of nonbent pressed samples revealed a network of flux-penetrated defect channels that were primarily oriented parallel to the tape axis. Bending such samples to a small strain increased the visibility of these defects, believed to be cracks. This network correlates well to the cracks produced in intermediate thermomechanical processing deformation steps. The greater sensitivity of the transport current of rolled samples to bending is further direct proof of the fact that the tape “remembers” the cracks induced in the core during intermediate deformation and that heat treatment after the deformation does not heal all damage. ©1997 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.118435

出版商:AIP    

年代:1997

数据来源: AIP