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排序方式: 共有135条查询结果,搜索用时 171 毫秒
31.
J. Nishizawa T. Sasaki K. Suto T. Tanabe T. Yoshida T. Kimura K. Saito 《International Journal of Infrared and Millimeter Waves》2006,27(6):779-789
We have constructed THz spectrometers using the widely frequency-tunable THz-wave generated from GaP crystal pumped at 1.2
μm region using two Cr:forsterite lasers and compared with that pumped at 1 μm region using a YAG laser and an optical parametric
oscillator (OPO). The systems have sufficient resolution for observation of solids and liquids at room temperature. We have
measured terahertz absorption spectra of all twenty kinds of amino acids which form proteins. 相似文献
32.
T. V. Torchinskaya 《Journal of Electronic Materials》1992,21(4):423-429
Complex kinetics of the injection-enhanced change of the GaP:N LED emitting power and transformation of luminescence and DLTS
spectra were investigated. It is shown that injection-enhanced processes in GaP:N LED’s includes: a) the interstitial defects
(Zni) diffusion from the highly doped layer near the contact into the active layer; b) the relief of stresses due to the arising
of a dislocation network and the generation of point defects (vacancies antisites); c) diffusion of the impurity atoms via
the vacancies which leads to dissociation of the nitrogen atom complexes (NN
i
). 相似文献
33.
Saturation of extrinsic photoconductivity in GaP:N(Zn, Te) diodes could be achieved by excitation with a TEA-CO2-laser. At wavelengths in the 10 m range intensities of several 100 kW/cm2 being near the damage threshold were applied. Carrier lifetimes of 60 ps at 4.2 K and 200 ps at 77 K could be estimated. The only conceivable mechanism explaining these short time constants is the capture of infrared excited holes by ionized shallow acceptors in the highly compensated p-side of the diode. 相似文献
34.
T. Niebling T. Lapp J. Kampmann P.J. Klar W. Heimbrodt B. Kunert K. Volz W. Stolz 《Physica E: Low-dimensional Systems and Nanostructures》2006,32(1-2):222
We present time-resolved photoluminescence (PL) results of a series of GaP1-xNx samples with x up to 0.01. The temperature dependence, the concentration dependence as well as the temporal behavior indicate that the PL is dominated by excitation transfer processes between the extended band states and localized N-related states (such as the isolated N-impurity, various N-pair states and higher N-clusters) as well as by excitation transfer between the various localized N-related states themselves. The excitation transfer processes in conjunction with the concentration-dependent statistics of the various N-related states alone are sufficient to explain the observed red-shift of the luminescence of GaP1-xNx with increasing x as well as the spectral dependence of the PL decay times. However, this implies that the PL data alone do not give any conclusive evidence that a hard transformation from an indirect to a direct-gap semiconductor takes place in Ga(N,P) with increasing N up to 2% as often stated. 相似文献
35.
The optical properties of indirect semiconductor quantum wells (QWs), were studied in relation to their electronic states controlled by an ultrathin AlP layer. The insertion of 1 ML of AlP at the center of a 60 Å GaAsP/GaP QW drastically increased the photoluminescence (PL) intensity and the efficiency of the no-phonon (NP) transition. The NP intensity relative to its TO phonon replica was found to greatly depend on the structural parameters and decreased by decreasing the width of the AlP layer or by increasing the arsenic composition of the GaAsP QW. The comparison with numerical calculation clarified that the efficiency of the NP transition is improved when the Xz electrons rather than Xxy electrons are involved in the radiative recombination. This can be qualitatively understood that the Xz electrons are more strongly localized to the AlP layer, leading to the efficient relaxation of the selection rule. The Arrhenius behavior of the PL intensity was also studied and the quenching of the PL intensity was interpreted as being due to the thermally activated escape of carriers from the well region into the GaP barrier. 相似文献
36.
利用基于密度泛函理论(DFT),采用赝势平面波方法和广义梯度近似法(GGA)研究了闪锌矿ZB结构和盐岩RS结构GaP的基态电子结构、光学性质,根据能带理论初步研究GaP基态能带结构、总态密度(DOS)和分波态密度(PDOS),并计算出吸收系数,反射率,复介电函数,复折射率及能量损失函数.还计算了闪锌矿结构的GaP的各向异性. 相似文献
37.
Orientation dependent etching of photolithographically patterned
GaP was investigated using solutions of HCl:CH3COOH:H2O2. The pattern was prepared using standard ultraviolet lithography and was a two-dimensional grid with an 18 μm repeat, consisting
of 15 μm squares separated by 3 μm spaces. The mask sides were aligned along the
and
directions. Under appropriate etching conditions, high quality arrays of pyramids were prepared. These pyramids were defined
by
,
and
facets. It was shown that the etching process depended on the degree of solution aging after initial mixing. For a freshly
prepared solution, the etching rate showed an inverse dependence on time. For short etching times (below 5 min), an intermediate
etching profile was followed, while for long times (greater than 5 min) etching was kinetically controlled. We demonstrated
that controlled etching at extremely low rates (0.1–0.5 μm/min) is feasible with this new approach. 相似文献
38.
39.
R. S. Bauer 《Journal of Electronic Materials》1975,4(5):1067-1078
We examine some relationships between defect characteristics and the modulated optical properties of solids. In particular,
the effects of an electric field ℰ on the N absorption in GaP are presented. The crystallographic-orientation dependence is
used to determine symmetry properties of the impurity electron states and their interaction with the host band structure.
These data also yield an impurity concentration which is in agreement (to within a factor of 2) with results obtained using
other techniques. The Franz-Keldysh mechanism responsible for the electro-absorption suggests that in indirect gap semiconductors,
an electric field should double the luminescence. This enhancement will be greatest for ℰ along the orbital axis of the luminescent
center. Generalizations of this work to other chemical and structural defects are discussed. 相似文献
40.
T. N. Morgan 《Journal of Electronic Materials》1975,4(5):1029-1036
Photo-ionization (P-I) from deep states in semiconductors can be used to explore the band structure of the crystal as well
as to give detailed information about the symmetry and other properties of the bound states themselves. When 2 electrons are
bound to a defect the P-I spectrum at high photon energy reflects the initial and final state properties of both electrons.
Only at low energies, where one electron is transferred into its 1-electron ground state does the P-I process of a 2-electron
state resemble that of a 1-electron state. This fact offers a resolution of the two different interpretations of P-I from
the 0- state in GaP as reported by Henry et al. from photo-capacitance studies and by Grimmeiss et al. from photo-conductivity.
In the latter the 4 lowest enercry thresholds (Ei = 0.65 to 1.19 eV) correspond to “1-electron” P-I with the 0 center left in its neutral ground state. Only above about 1.4
eV do the “2-electron” processes appear. In photo-capacitance the “2-electron” processes dominate (the “1-electron” thresholds
being too weak or too diffuse to be identified), and the spectrum is strongly modified by relaxation of the lattice around
the 0+ ion. 相似文献