共查询到13条相似文献,搜索用时 0 毫秒
1.
G. W. Iseler 《Journal of Electronic Materials》1984,13(6):989-1011
By reducing the temperature gradients in the vicinity of the crystal-melt interface, 35-mm-diameter InP boules with much reduced
dislocation densities have been grown by the liquid-encapsulated Czochralski technique. A reduction in the residual donor
concentration of InP grown by this technique has been achieved by using In-rich charges prepared by adding elemental In to
polycrystalline InP ingot material. Nominally undoped crystals with carrier concentrations as low as 1–2 x4 1015 Cm − 1 and 77 K mobilities as high as 7.0 × 10 cm2 V−1 s−1 have been obtained. By growing doped crystals at increased seed or crucible rotation rates, short-range longitudinal variations
in dopant concentration have been reduced to a few per cent, as determined by optical absorption measurements with a scanning
CO2 laser. 相似文献
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对比了用温度梯度溶液法生长的未掺杂、Cr和In掺杂的ZnTe晶体的性能。Cr及In掺杂后ZnTe的吸收边都发生了红移。Cr掺杂在晶体中引入两个特征吸收峰,一个位于约1750 nm,而另一个位于紧挨吸收边的低能一侧。但是本征吸收区域的反射光谱对掺杂并不敏感。未掺杂,Cr掺杂和In掺杂晶体的电阻率分别为10^2 Ω·cm ,103 Ω·cm和10^8 Ω·cm。只有In掺杂的晶体在500-4000 cm^-1范围内红外透过率高于60%。但是Cr掺杂晶体的红外透过率随波数的增加而快速下降,这是因为Cr在ZnTe晶体中的固溶度很低,Cr掺杂后在晶体中会引入一些结构缺陷会对红外光造成散射。 相似文献
6.
Ta2O5 single crystals have been grown by the laser heated pedestal growth (LHPG) technique up to several centimeters length with diameter of 1.1 mm. The crystal, characterized by X-ray diffraction, dielectric measurement, and thermal expansion analysis, has Htri-Wa2O5 symmetry. Dielectric permittivity, loss tangent along [001] and [110] direction were investigated over the temperature range from -180℃ to 100℃. Large dielectric anisotropy in 2O5 single crystal was observed. At room temperature, the dielectric permittivities (1 MHz) along [001] and [110] are 33.2 and 231.9, respectively. The reason of dielectric enhancement in Ta2O5 crystal grown by LHPG was also discussed. 相似文献
7.
Yijian Jiang Ruyan Guo and A.S.Bhalla Institute of Laser Engineering Beijing University of Technology Beijing Materials Research Laboratory The Pennsylvania State University University Park PA USA 《中国激光》2008,(11)
Ta2O5 single crystals have been grown by the laser heated pedestal growth (LHPG) technique up to several centimeters length with diameter of 1.1 mm. The crystal, characterized by X-ray diffraction, dielectric measurement, and thermal expansion analysis, has Htri-Ta2O5 symmetry. Dielectric permittivity, loss tangent along [001] and [110] direction were investigated over the temperature range from -80 ℃ to 100 ℃. Large dielectric anisotropy in Ta2O5 single crystal was observed. At room temperature, the dielectric permittivities (1 MHz) along [001] and [110] are 33.2 and 231.9, respectively. The reason of dielectric enhancement in Ta2O5 crystal grown by LHPG was also discussed. 相似文献
8.
Crystal quality of 2′ Φ S doped InP substrates grown by the conventional liquid encapsulated Czochralski method was studied
by the photoluminescence mapping technique and double crystal x-ray diffraction method. Dark currents of InGaAs/InP PIN-photodiodes
(PIN-PDs) fabricated on them showed the existence of an anomaly at the center of the substrate. Photoluminescence intensity
abruptly decreased at the center of the substrate. An abnormal curvature of the lattice plane was found at the center of the
substrate by the double crystal x-ray diffraction measurement. We discuss the correlation between crystal quality of the substrate
and dark currents of PIN-PDs. 相似文献
9.
K. Yasuda K. Mori Y. Kubota K. Kojima F. Inukai Y. Asai T. Nimura 《Journal of Electronic Materials》1998,27(8):948-953
Growth characteristics of (100)-oriented CdZnTe layers grown by atmospheric-pressure metalorganic vapor phase epitaxy have
been studied using dimethylzinc (DMZn), dimethylcadmium (DMCd), diethyltelluride (DETe), and dimethyltelluride (DMTe) as precursors.
Variations of Zn composition and layer growth rate were examined by changing the DMZn supply ratio, defined as DMZn/(DMCd+DMZn),
where the precursors are expressed in appropriate units of flow rate, from 0 (no DMZn) to 1.0 (no DMCd), while keeping the
total group II supply rate constant. The growth rate of CdZnTe layers was found to decrease monotonically with increase of
the DMZn supply ratio. On the other hand, the Zn composition x of grown layers increased gradually up to x=0.04 with increase
of the DMZn supply ratio from 0 to 0.8, beyond which the Zn composition increased abruptly to ZnTe. The abrupt transition
of Zn composition was suppressed by increasing the VI/II ratio. The growth mechanism of CdZnTe layers was studied based on
the observed growth characteristics of CdTe and ZnTe. A higher desorption rate from the growth surface for Zn species than
for Cd species, and a higher rate of CdTe formation than ZnTe formation are believed to cause the observed growth characteristics.
CdZnTe layers with high crystal quality were grown in a wide range of Zn compositions. The full-width at half-maximum values
for x-ray double-crystal rocking-curve measurements were lower than 320 arc-sec for x<0.3 and x>0.75. 相似文献
10.
The adsorption of CdTe layers on clean and As-passivated Si(211) substrates has been simulated by first-principle calculations
in this study. Based on the simulation results, we theoretically show the important roles of the As4 passivation during the epitaxial growth. Arsenic can saturate part of the dangling bonds and weaken the surface states. The
partial passivation finally induces the B-face polarity selection automatically. This conclusion can provide further explanations
for the successful growth of large area high-quality CdTe(211)B layers on the Si(211) substrates. 相似文献
11.
Y. P. Chen G. Brill E. M. Campo T. Hierl J. C. M. Hwang N. K. Dhar 《Journal of Electronic Materials》2004,33(6):498-502
We report on the first successful growth of the quaternary alloy Cd1−yZnySexTe1−x(211) on 3-in. Si(211) substrates using molecular beam epitaxy (MBE). The growth of CdZnSeTe was performed using a compound
CdTe effusion source, a compound ZnTe source, and an elemental Se effusion source. The alloy compositions (x and y) of the
Cd1−yZnySexTe1−x quaternary compound were controlled through the Se/CdTe and ZnTe/CdTe flux ratios, respectively. Our results indicated that
the surface morphology of CdZnSeTe improves as the Zn concentration decreases, which fits well with our previous observation
that the surface morphology of CdZnTe/Si is poorer than that of CdSeTe/Si. Although the x-ray full-width at half-maximums
(FWHMs) of CdZnSeTe/Si with 4% of Zn + Se remain relatively constant regardless of the individual Zn and Se concentrations,
etched-pit density (EPD) measurements exhibit a higher dislocation count on CdZnSeTe/Si layers with about 2% Zn and Se incorporated.
The enhancement of threading dislocations in these alloys might be due to an alloy disorder effect between ZnSe and CdTe phases.
Our results indicate that the CdZnSeTe/Si quaternary material with low Zn or low Se concentration (less than 1.5%) while maintaining
4% total Zn + Se concentration can be used as lattice-matching composite substrates for long-wavelength infrared (LWIR) HgCdTe
as an alternative for CdZnTe/Si or CdSeTe/Si. 相似文献
12.
H. Hermon M. Schieber R. B. James E. Y. Lee N. Yang A. J. Antolak D. H. Morse C. Hackett E. Tarver N. N. P. Kolesnikov Yu N. Ivanov V. Komar M. S. Goorsky H. Yoon 《Journal of Electronic Materials》1999,28(6):688-694
Sandia National Laboratories (SNL) is leading an effort to evaluate vertical high pressure Bridgman (VHPB) Cd1−xZnxTe (CZT) crystals grown in the former Soviet Union (FSU) (Ukraine and Russia), in order to study the parameters limiting the
crystal quality and the radiation detector performance. The stoichiometry of the CZT crystals, with 0.04<x<0.25, has been
determined by methods such as proton-induced x-ray emission (PIXE), x-ray diffraction (XRD), microprobe analysis and laser
ablation ICP mass spectroscopy (LA-ICP/MS). Other methods such as triaxial double crystal x-ray diffraction (TADXRD), infrared
transmission spectroscopy (IR), atomic force microscopy (AFM), thermoelectric emission spectroscopy (TEES) and laser induced
transient charge technique (TCT) were also used to evaluate the material properties. We have measured the zinc distribution
in a CZT ingot along the axial direction and also its homogeneity. The (Cd+Zn)/Te average ratio measured on the Ukraine crystals
was 1.2, compared to the ratio of 0.9–1.06 on the Russian ingots. The IR transmission showed highly decorated grain boundaries
with precipitates and hollow bubbles. Microprobe elemental analysis and LA-ICP/MS showed carbon precipitates in the CZT bulk
and carbon deposits along grain boundaries. The higher concentration of impurities and the imperfect crystallinity lead to
shorter electron and hole lifetimes in the range of 0.5–2 and 0.1 μs, respectively, compared to 3–20 and 1–7 μs measured on
U.S. spectrometer grade CZT detectors. These results are consistent with the lower resistivity and worse crystalline perfection
of these crystals, compared to U.S.-grown CZT. However, recently grown CZT from FSU exhibited better detector performance
and good response to alpha particles. 相似文献
13.
R. Niebuhr K. Bachem K. Dombrowski M. Maier W. Pletschen U. Kaufmann 《Journal of Electronic Materials》1995,24(11):1531-1534
We have studied the growth of gallium nitride on c-plane sapphire substrates. The layers were grown in a horizontal metalorganic
chemical vapor deposition reactor at atmospheric pressure using trimethylgallium (TMG) and ammonia (NH3). Variation of the V/III ratio (150–2500) shows a distinct effect on the growth rate. With decreasing V/III ratio, we find
an increasing growth rate. Variation of the growth temperature (700–1000°C) shows a weak increase in growth rate with temperature.
Furthermore, we performed secondary ion mass spectroscopy measurements and find an increasing carbon incorporation in the
GaN films with decreasing ammonia partial pressure and a growing accumulation of carbon at the substrate interface. Photoluminescence
measurements show that samples with high carbon content show a strong yellow luminescence peaking at 2.2 eV and a near band
gap emission at 3.31 eV. With increasing carbon content, the intensity of the 3.31 eV line increases suggesting that a carbon
related center is involved. 相似文献