摘要:

Integrated structures consisting of twoP‐I‐Ndouble heterostructure GaAs photodetectors, series connected by means of a tunnel junction, have been fabricated by molecular beam epitaxy. Open‐circuit output voltages, external power efficiencies, and fill factors were 1.777 V, 33.4%, and 0.83, respectively, for antireflection‐coated cells excited by ∼5 mW optical power from a focused DH AlGaAs laser emitting at &lgr;=0.815 &mgr;m.

ISSN:0003-6951    

DOI:10.1063/1.90443

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

The reflectivity of single‐crystal and amorphous GaAs samples was measured in the photon energy range 1.5–7.0 eV. The amorphous specimens were obtained by 400‐keV Te implantation at room temperature. Some structures at high photon energy are still present in the imaginary part of the dielectric function for the Te‐implanted GaAs. The optical properties of such an amorphous layer differ noticeably from those reported in literature for flash‐evaporated films. The difference may be attributed to the lack of stoichiometry in the deposited layers.

ISSN:0003-6951    

DOI:10.1063/1.90444

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A high‐throughput diffraction‐limited chirp‐grating Bragg diffraction lens for guided‐wave optical device applications has been demonstrated with planar photolithographic fabrication techniques. Diffraction‐limited performance has been obtained with a 2‐mm‐aperturef/16 lens focusing the He‐Ne laser beam to a 6.1‐&mgr;m spot size. The grating diffraction efficiency to the focus is over 90%. This type of lens has predictable focusing properties which are insensitive to process variations, an important consideration for accurately aligned integrated optical systems.

ISSN:0003-6951    

DOI:10.1063/1.90445

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Substantial improvements in energy conversion efficiency are reported for silicon MIS solar cells fabricated on both single‐crystalline and semicrystalline substrates. Based on active area, AM1 efficiencies of 15.1% and 12.6%, respectively, have been obtained for 3.1‐cm2cells at 26 °C.

ISSN:0003-6951    

DOI:10.1063/1.90446

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

A newp‐nphotodetector operating at room temperature and sensitive in the near infrared for wavelengths as long as 1.6 &mgr;m has been made from Ga0.47In0.53As grown lattice matched on InP substrates by LPE. These detectors display avalanche gain and dark current as low as 2×10−9A. Measurements of the speed of response at 1.06 &mgr;m have shown a detector response time as fast as 250 psec.

ISSN:0003-6951    

DOI:10.1063/1.90447

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Efficient indium tin oxide (ITO)/polycrystalline silicon heterojunction solar cells have been fabricated utilizing neutralized ion‐beam sputtering techniques. These cells were fabricated on single‐pass float‐zone‐refined silicon. Conversion efficiencies of 6.25% under AM1 illumination have been observed. Cells were analyzed byI‐Vcharacteristics and a scanning laser photoresponse technique. Qualitative minority‐carrier lifetime has been mapped using the EBIC mode of a SEM. This has revealed a reduced photoresponse at the grain boundaries independent of grain size, and also at defect clusters within individual grains. Surface blemishes and etch pits are not important in reducing the cell photoresponse. It appears that the low‐temperature processing inherent in semiconductor‐insulator‐semiconductor solar cells is applicable to polycrystalline material.

ISSN:0003-6951    

DOI:10.1063/1.90448

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Temporal pulse splitting has been observed at an aperture 8 m from a passively mode‐locked Nd : YAG laser oscillator. A theoretical model using the published value of the nonlinear refractive indexn2of YAG shows the splitting mechanism.

ISSN:0003-6951    

DOI:10.1063/1.90449

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Lasing action was observed on the 3d4p 1F30→4s3d 1D2and 4p2 1D2→4s4p 1P10atomic transitions in calcium at 535 and 586 nm, respectively, when mixtures of atomic calcium and an inert gas were irradiated by a focused KrF laser (249 nm). No lasing was observed when the inert‐gas collision partner was absent. The upper laser levels in these systems are not optically connected to the1S0ground state and thereby may be accessed via transitions in the inert‐gas/calcium quasimolecule by absorption of KrF laser light in the wings of the 4s21S0to 4s6p 1P10calcium 2398.56‐A˚ resonance transition (collision‐induced absorption). The pump laser was a modified Tachisto using unstable cavity optics which provided focused intensities of nearly 1 GW/cm2. The calcium was produced in a stainless‐steel heat pipe oven at temperatures near 1200 °K. Buffer gases studied include He, Ar, and Kr.

ISSN:0003-6951    

DOI:10.1063/1.90450

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

We report the formation of Ohmic contacts ton‐GaAs without the need for a high‐temperature alloy. Heavily dopedn‐GaAs(Sn) was grown using molecular beam epitaxy in which the concentration of free carriers was as high as ‖ND−NA‖=6×1019cm−3yielding specific contact resistancerc=1.86×10−6&OHgr;‐cm2.

ISSN:0003-6951    

DOI:10.1063/1.90451

出版商:AIP    

年代:1978

数据来源: AIP

摘要:

Approximate expressions are presented which are useful for computing the position of the Fermi level in a semiconductor when the carrier concentration is known. A simple approximation formula is applicable for &eegr;=EF/kT⩽5.7, while an extended approximation can be used up to &eegr;⩽20, the error inEFbeing less than 10−2kTin both cases.

ISSN:0003-6951    

DOI:10.1063/1.90452

出版商:AIP    

年代:1978

数据来源: AIP