摘要:

Electron‐electron scattering of ballistic electrons in a two‐dimensional electron gas was studied as a function of the electron excess energy above the Fermi energy and of temperature. At low temperatures of 1.4 K it is found that for excess energies of approximately 30% of the Fermi energy the electrons in a ballistic electron beam are already scattered significantly due to electron‐electron interaction. A very good agreement between our experimental data and theory was found, when the measured data were compared with numerical calculations based on a theory of Giuliani and Quinn [Phys. Rev. B26, 4421 (1982)], while the agreement was only poor for the analytical approximation of the electron‐electron scattering rate. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113801

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We present a steady‐state phenomenological rate equation model describing the temperature dependence of the threshold current and slope efficiency of compressively strained InGaAsP multiquantum well lasers. The model is supported by measurements of differential carrier lifetime and gain carried out as a function of temperature. Differential gain, carrier density at transparency, and internal losses are shown to be the key parameters controlling the temperature sensitivity of our devices. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113802

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report the results of aninsituspectroscopic ellipsometry study concerning the substrate dependence of the evolution of microcrystalline silicon films deposited by alternating amorphous silicon deposition and hydrogen plasma treatment. The evolution of the composition of the films during growth, up to thicknesses of ∼100 nm, indicates that besides etching, the diffusion of atomic hydrogen efficiently promotes the growth (and/or nucleation) of buried crystallites. Moreover, the evolution of the films strongly depends on the nature of the substrate. This substrate selectivity is discussed in terms of initial growth processes. The effect of the hydrogen plasma well below the film surface, which produces the thickness‐dependent film composition, along with the substrate selectivity, may be of prime importance in technological applications of microcrystalline silicon. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113803

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The fabrication of 3C‐SiC and 6H‐SiCpnjunction diodes, grown side by side on low‐tilt‐angle 6H‐SiC substrates via a chemical vapor deposition (CVD) process, has recently been reported. Admittance spectroscopy and deep‐level transient spectroscopy (DLTS) measurements were made on one of these diodes to compare the defect structure of 3C‐ and 6H‐SiC CVD epitaxial layers grown under the same conditions. The 6H‐SiC layers revealed a single minority carrier level and a deeper broad majority carrier peak. The minority level is due to the boron‐relatedDcenter, whereas the broad majority level was identified as a double peak by a DLTS simulation. DLTS measurements on the 3C‐SiC layers revealed only one deep level impurity consistent with the boron‐relatedDcenter. Shallow donor levels observed using admittance spectroscopy correspond with the known shallow nitrogen donor in both 3C‐ and 6H‐SiC epitaxial layers. This confirms that both 3C‐ and 6H‐SiC polytypes were simultaneously formed on the same 6H‐SiC substrate. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113804

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The optical response of PtSi/p‐Si Schottky barrier detectors structured with a lamellar grating was investigated. The quantum efficiencyYfor TE and TM polarized light for different samples with grating constants &Lgr;=3 &mgr;m, 4 &mgr;m, 5 &mgr;m, and with a grating amplitudeh=1100 nm was measured. The ratioYTM/YTEstrongly depends on the back bias of the diode. Theoretical calculations are presented which explain the results taking into account the locally varying Schottky barrier height and optical absorption induced by the grating. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113805

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have measured the drift mobility of electrons and holes in thin, vapor‐deposited films oftris(8‐hydroxyquinolinolato‐N1,O8) aluminum using a time of flight photoconductivity technique. The drift of mobility of both carriers is dispersive and strongly electric field and temperature dependent. At ambient temperature and an electric field of 4×105V cm−1, the effective mobility of electrons and holes is 1.4×10−6and 2×10−8 cm2 V−1 s−1, respectively, in a 400 nm thick sample. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113806

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report experimental and theoretical evidence for electrostatic lateral confinement induced by a nanoprobe. The lateral confinement is manifest as oscillations of the differential conductance of a near‐surface resonant‐tunneling heterostructure in air at room temperature. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113807

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

CdS thin films deposited from chemical bath containing citratocadmium(II) and thiourea are intrinsic and highly photosensitive. In the present letter, we discuss the conversion of such films tontype by thermal diffusion of indium from an evaporated 50 nm indium film deposited on the CdS thin film. The process which takes place in the temperature range of 250 °C–350 °C involves the formation of an In2O3surface layer which acts as a barrier preventing the outdiffusion of indium. This allows indium to diffuse into the CdS film and results in an indium‐doped CdS thin film. The electrical conductivity of such films is about 300 &OHgr;−1 cm−1. All beneficial optical properties of chemically deposited CdS thin films for application as a window material in heterojunction optoelectronic devices are retained. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113808

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We report on the application of the atomic force microscope (AFM) to manipulate and position nanometer‐sized particles with nanometer precision. The technique, which can be regarded as a nanometer‐scale analogy to atomic level manipulation with the scanning tunneling microscope, allowed us to form arbitrary nanostructures, under ambient conditions, by controlled manipulation of individual 30 nm GaAs particles. A whole new set of nanodevices can be fabricated particle‐by‐particle for studies of quantum effects and single electron tunneling. We also demonstrate a method, based on the AFM manipulation, to determine the true lateral dimensions of nano‐objects, in spite of the tip‐sample convolution. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113809

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Temperature dependence of luminescence was measured in InPxAs1−x:Yb crystals (x=7% and 12%) and in reference undoped material (x=8%). A simple correlation between Yb doping and the number of thermally activated bands in the near‐band‐edge spectral region of In(P,As) alloys was found. A new luminescence band located at ∼25 meV below the free‐carrier, band‐to‐band emission was observed in Yb‐doped alloys only. A one‐to‐one correspondence between the appearance of this band and the quenching of the intra‐4f‐shell photoluminescence of Yb3+ions is shown. These observations are taken as direct evidence for participation of excitons bound on Yb3+ion in the excitation and quenching processes of the 4fshell. ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.114122

出版商:AIP    

年代:1995

数据来源: AIP