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1.
S. -H. Park K. -B. Kim S. -Y. Seo S. -H. Kim S. -W. Han 《Journal of Electronic Materials》2006,35(8):1680-1684
We present the structural and optical properties of Zn1?xMgxO thin films studied using x-ray diffraction (XRD), extended x-ray absorption fine structure (EXAFS), and photoluminescence (PL) measurements. The Zn1?xMgxO films on sapphire [0001] substrates were fabricated with metal organic chemical vapor deposition (MOCVD). The XRD measurements showed that the Zn1?xMgxO films (x≤0.05) had a wurtzite structure without any MgO phase and were epitaxially grown along the c-axis of the Al2O3 substrate. The lattice constant of the Zn0.95Mg0.05O film shrank by 0.023 Å, compared with that of ZnO crystals. From the EXAFS measurements on the Zn1?xMgxO films at Zn K-edge, we found a substantial amount of distortion in the bond length of Zn-Zn pairs with a small amount of Mg substitution on the Zn site. The PL measurements showed a gradual increment of the main exciton transitions from 3.36 eV (x=0.0) to 3.57 eV (x=0.05) at 10 K. We also observed a strong deep-level emission near 2.3 eV from the specimen with x=0.05. 相似文献
2.
Jae-Hong Lim Mi Yeong Park Dong Chan Lim Bongyoung Yoo Jung-Ho Lee Nosang V. Myung Kyu Hwan Lee 《Journal of Electronic Materials》2011,40(5):1321-1325
Thermoelectric Sb
x
Te
y
films were potentiostatically electrodeposited in aqueous nitric acid electrolyte solutions containing different concentrations
of TeO2. Stoichiometric Sb
x
Te
y
films were obtained by applying a voltage of −0.15 V versus saturated calomel electrode (SCE) using a solution consisting
of 2.4 mM TeO2, 0.8 mM Sb2O3, 33 mM tartaric acid, and 1 M HNO3. The nearly stoichiometric Sb2Te3 films had a rhombohedral structure, R[`3]m R\bar{3}m , with a preferred orientation along the (015) direction. The films had hole concentration of 5.8 × 1018/cm3 and exhibited mobility of 54.8 cm2/Vs. A more negative potential resulted in higher Sb content in the deposited Sb
x
Te
y
films. Furthermore, it was observed that the hole concentration and mobility decreased with increasingly negative deposition
potential, and eventually showed insulating properties, possibly due to increased defect formation. The absolute value of
the Seebeck coefficient of the as-deposited Sb2Te3 thin film at room temperature was 118 μV/K. 相似文献
3.
SiN
x
:H films of different compositions grown on glass and silicon substrates using plasma-chemical vapor deposition at a temperature
of 380°C have been subjected to pulsed laser annealings. The treatments are performed using titanium-sapphire laser radiation
with a wavelength of 800 nm and a pulse duration of 30 fs. Structural changes in the films are studied using Raman spectroscopy.
Amorphous silicon nanoclusters are detected in as-grown films with molar fractions of excess silicon of ∼1/5 and larger. Conditions
required for pulsed crystallization of nanoclusters were determined. According to the Raman data, no silicon clusters were
detected in as-grown films with a small amount of excess silicon (x > 1.25). Pulsed treatments resulted in the formation of silicon nanoclusters 1–2 nm in size in these films. 相似文献
4.
N. A. Vlasenko N. V. Sopinskii E. G. Gule V. V. Strelchuk P. F. Oleksenko L. I. Veligura A. S. Nikolenko M. A. Mukhlyo 《Semiconductors》2012,46(3):323-329
The photoluminescence of SiO
x
films deposited on c-Si wafers by the thermal evaporation of SiO in a vacuum and, for the first time, doped with ErF3 by coevaporation is studied. It is shown that, like undoped SiO
x
films, the unannealed SiO
x
:ErF3 films passivate the surface of the Si wafers and, thus, increase their edge photoluminescence intensity almost fivefold.
A similar increase is observed after annealing of the doped films in air at 750°C. Doping with ErF3 suppresses the photoluminescence of Si nanoclusters, if the films have been subjected to high-temperature annealing (at 750°C).
In this case, the PL intensity of the band with a peak at ∼890 nm decreases as well. The ∼890 nm band is observed for the
first time and, due to its features, is attributed to transitions in SiO
x
matrix defects. The experimentally observed effect of ErF3 doping on SiO
x
film photoluminescence is interpreted. An intense photoluminescence signal from Er3+ ions in the nearinfrared spectral region (the 4
I
11/2 → 4
I
15/2 and 4
I
13/2 → 4
I
15/2 transitions) is observed in the SiO
x
:ErF3 films annealed in air at 750°C. This finding shows that 1.54 μm luminescent emitters, which are currently in popular demand,
can be produced by a simple low-cost method. 相似文献
5.
Thermoelectric materials are attractive since they can recover waste heat directly in the form of electricity. In this study,
the thermoelectric properties of ternary rare-earth sulfides LaGd1+x
S3 (x = 0.00 to 0.03) and SmGd1+x
S3 (x = 0.00 to 0.06) were investigated over the temperature range of 300 K to 953 K. These sulfides were prepared by CS2 sulfurization, and samples were consolidated by pressure-assisted sintering to obtain dense compacts. The sintered compacts
of LaGd1+x
S3 were n-type metal-like conductors with a thermal conductivity of less than 1.7 W K−1 m−1. Their thermoelectric figure of merit ZT was improved by tuning the chemical composition (self-doping). The optimized ZT value of 0.4 was obtained in LaGd1.02S3 at 953 K. The sintered compacts of SmGd1+x
S3 were n-type hopping conductors with a thermal conductivity of less than 0.8 W K−1 m−1. Their ZT value increased significantly with temperature. In SmGd1+x
S3, the ZT value of 0.3 was attained at 953 K. 相似文献
6.
The results of the first studies of the effect of selective etching on photoluminescence in porous nc- Si–SiOx structures containing Si nanoclusters (nc-Si) in the SiOx matrix are reported. In the initial samples at room temperature, intense photoluminescence bands are observed with peaks
at 840 and 660 nm corresponding to radiative recombination of free charge carriers (or charge carriers bound to excitons)
excited in nc- Si. After selective etching of the nc- Si–SiOx structures in 1% HF solution, these bands are noticeably shifted to higher energies of the spectrum. It is suggested that
the evolution of the spectra is due to the decrease in the Si nanoparticle dimensions on etching of the oxide and additional
oxidation of nc- Si. The results show that selective etching of the oxide matrix can be used to control the radiation spectra of porous nc- Si–SiOx structures. 相似文献
7.
N. A. Vlasenko N. V. Sopinskii E. G. Gule E. G. Manoilov P. F. Oleksenko L. I. Veligura M. A. Mukhlyo 《Semiconductors》2011,45(11):1414-1419
A band with a peak at 890 nm is detected in the photoluminescence spectra of SiO
x
(x ≈ 1.3) films deposited by thermal evaporation of SiO and annealed in air at 650–1150°C. The 890-nm band appears after low-temperature
(∼650°C) annealing and exhibits a number of features: (i) as the annealing temperature is elevated to 1150°C, the position
of the band peak remains unchanged, whereas the intensity increases by two orders of magnitude; (ii) the effects of the annealing
atmosphere (air, vacuum) and the excitation wavelength and power density on the intensity of the 890-nm band differ from the
corresponding effects on the well-known bands observable in the ranges 600–650 and 700–800 nm; and (iii) the photoluminescence
decay is first fast and then much slower, with corresponding lifetimes of ∼9 and ∼70 μs. The observed features are inconsistent
with the interpretation of photoluminescence observed in SiO
x
so far. Specifically, the earlier observed photoluminescence was attributed to transitions between the band and defect states
in the matrix and between the states of band tails, transitions inside Si nanoclusters, and intraion transitions in rare-earth
impurity ions. Therefore, we consider here the possibility of attributing the 890-nm band to transitions in local centers
formed by silicon ions twofold- and/or threefold-coordinated with oxygen; i.e., we attempt to interpret the 890-nm band in
the same manner as was done for luminescence in SiO2 glasses and films slightly deficient in oxygen. 相似文献
8.
Mg2Sn compounds were prepared by the modified vertical Bridgman method, and were doped with Bi and Ag to obtain n- and p-type materials, respectively. Excess Mg was also added to some of the ingots to compensate for the loss of Mg during the
preparation process. The Mg2Sn samples were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM), and their power factors were
calculated from the Seebeck coefficient and electrical conductivity, measured from 80 K to 700 K. The sample prepared with
4% excess Mg, which contains a small amount of Mg2Sn + Mg eutectic phase, had the highest power factor of 12 × 10−3 W m−1 K−2 at 115 K, while the sample doped with 2% Ag, in which a small amount of eutectics also exists, has a power factor of 4 × 10−3 W m−1 K−2 at 420 K. 相似文献
9.
Y. Isoda S. Tada T. Nagai H. Fujiu Y. Shinohara 《Journal of Electronic Materials》2010,39(9):1531-1535
Mg2Si1−x
Sn
x
-system solid solutions are ecofriendly semiconductors that are promising materials for thermoelectric generators in the middle
temperature range. To produce a thermoelectric device, high-performance p- and n-type materials must be balanced. In this paper, p-type Mg2.00Si0.25Sn0.75 with Li and Ag double doping was prepared by the liquid–solid reaction method and hot-pressing. Effects of Li and Ag double
doping on thermoelectric properties were investigated in the temperature range from room temperature to 850 K. All sintered
compacts were identified as single-phase solid solutions with anti-fluorite structure. The carrier concentration increased
with the double doping. The temperature dependence of resistivity of the double-doped samples was similar to that of a metal.
The seebeck coefficient increased with temperature to a maximum value and then decreased in the intrinsic region. Thermal
conductivity decreased linearly with increasing temperature, reaching a minimum near the intrinsic region, and then increased
rapidly because of the contribution of the bipolar component. The dimensionless figure of merit reached 0.32 at 610 K for
Mg2.00Si0.25Sn0.75 double-doped with Li-5000 ppm and Ag-20000 ppm. 相似文献
10.
In this report, we present a new secondary ion mass spectrometry (SIMS) analysis technique to provide accurate Cd composition
profiles based on the measurement of HgCs+ and CdCs+ cluster ions. Study of Hg1–x
Cd
x
Te samples with different x values shows that x/(1 − x) is linearly proportional to HgCs+/CdCs+ over the range of x = 0.2 to x = 0.9. This technique allows us to obtain an accurate Cd profile for a multilayer HgCdTe sample with different x values for each layer using a single standard with known x value.
(Received 10/15/06; accepted 2/14/07) 相似文献
11.
We report on the ultraviolet (UV) photodetection properties of a Pt contact on a sol-gel Mg0.1Zn0.9O/ZnO composite structure on a glass substrate. In the dark, the current–voltage (I–V) characteristics between the Pt and Ag contacts on the top of the ZnO film were linear while that on the Mg0.1Zn0.9O/ZnO composite film were rectifying, suggesting the formation of a Schottky diode on the latter. The ideality factor, n, and the reverse leakage current density, J
R
, of the Schottky diode were greater than 2 and 2.36 × 10−2 A cm−2 at −5 V, respectively. Under ultraviolet light, the I–V characteristics become linear. The maximum photo-to-dark current ratio observed was about 63. The composite film showed good
sensitivity to UV light with wavelengths of less than 400 nm, though the photoresponse process was found to be slow. 相似文献
12.
The effects of atomic hydrogen (H) and Br/methanol etching on Hg1−x
Cd
x
Te films were investigated using x-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Exposure of an
as-received Hg1−x
Cd
x
Te sample to H + H2 resulted in H-induced TeO2 reduction. The oxide reduction was first order with respect to H + H2 exposure. Exposure to H + H2 after etching the Hg1−x
Cd
x
Te film in a Br/methanol solution induced Hg and C depletion. Hg and C removal was also observed after completely reducing
the TeO2 on the as-received sample. The removal process was hindered by the formation of a Cd-rich overlayer on both etched and unetched
surfaces. 相似文献
13.
H. Sheng G. Saraf N. W. Emanetoglu D. H. Hill Y. Lu 《Journal of Electronic Materials》2005,34(6):754-757
The Al nonalloyed ohmic contacts were fabricated on MgxZn1−xO (0≤x≤0.2) thin films. HCl surface treatment significantly reduced the specific contact resistances to value around 10−4 Ω cm2. X-ray photoelectron spectroscopy (XPS) analysis revealed that the HCl treatment increased the oxygen vacancy density and
introduced chlorine to the semiconductor surface, resulting in a thin conductive layer and thus reduced specific contact resistance.
A subsequent oxygen plasma treatment reduced the oxygen vacancy density, and correspondingly increased the specific contact
resistance. Al-ZnO contacts were insensitive to the HCl treatment, due to the formation of a highly conductive Al-doped thin
interface layer. 相似文献
14.
A. Bhatia W.M. Hlaing Oo G. Siegel P.R. Stone K.M. Yu M.A. Scarpulla 《Journal of Electronic Materials》2012,41(5):837-844
Ge1−x
Sn
x
thin films are interesting for all-group-IV optoelectronics because of a crossover to a direct bandgap with dilute Sn alloying.
However, Sn has vanishing room-temperature equilibrium solubility in Ge, making their synthesis very challenging. Herein,
we report on our attempts to synthesize Ge1−x
Sn
x
films on Ge (001) using ion implantation and pulsed laser melting (II-PLM). A maximum of 2 at.% Sn was incorporated with
our experimental conditions in the samples as determined by Rutherford back scattering spectroscopy. A red-shift in the Ge
optical phonon branch and increased absorption below the Ge bandgap with increasing Sn concentration indicate Sn-induced lattice-
and band-structure changes after II-PLM. However, ion-channeling and electron microscopy show that the films are not of sufficient
epitaxial quality for use in devices. 相似文献
15.
A reaction study of Cu
x
Ni
y
alloy (x = 0.2–0.95) under bump metallization (UBM) with Sn-Ag-zCu solder (z = 0–0.7) was conducted. Formation and separation of intermetallic compounds (IMCs), effect of Cu addition to the Cu
x
Ni
y
alloy and the solders, and compatibility of reaction products with currently available phase diagrams are extensively investigated.
The increase of Cu content both in the Cu
x
Ni
y
alloy and in the solder promoted IMC growth and Cu
x
Ni
y
consumption; though, with regard to solder composition, the reverse trend was true of the solder reactions in the literature.
The liquid + Cu6Sn5 area in the Sn-rich corner needs to be larger compared to the currently available Cu-Ni-Sn ternary phase diagram, and the
maximum simultaneous soluble point of Ni and Cu in Sn needs also to be moved to the Ni-Sn side (e.g., Sn-0.6Cu-0.3Ni). 相似文献
16.
Transparent semiconductor thin films of Zn1−x
Mg
x
O (0 ≤ x ≤ 0.36) were prepared using a sol–gel process; the crystallinity levels, microstructures, and optical properties affected
by Mg content were studied. The experimental results showed that addition of Mg species in ZnO films markedly decreased the
surface roughness and improved transparency in the visible range. A Zn1−x
Mg
x
O film with an x-value of 0.2 exhibited the best average transmittance, namely 93.7%, and a root-mean-square (RMS) roughness of 1.63 nm. Therefore,
thin-film transistors (TFTs) with a Zn0.8Mg0.2O active channel layer were fabricated and found to have n-type enhancement mode. The Zn0.8Mg0.2O TFT had a field-effect mobility of 0.1 cm2/V s, threshold voltage of 6.0 V, and drain current on/off ratio of more than 107. 相似文献
17.
Ternary rare-earth sulfides NdGd1+x
S3, where 0 ≤ x ≤ 0.08, were prepared by sulfurizing Ln2O3 (Ln = Nd, Gd) with CS2 gas, followed by reaction sintering. The sintered samples have full density and homogeneous compositions. The Seebeck coefficient,
electrical resistivity, and thermal conductivity were measured over the temperature range of 300 K to 950 K. All the sintered
samples exhibit a negative Seebeck coefficient. The magnitude of the Seebeck coefficient and the electrical resistivity decrease
systematically with increasing Gd content. The thermal conductivity of all the sintered samples is less than 1.9 W K−1 m−1. The highest figure of merit ZT of 0.51 was found in NdGd1.02S3 at 950 K. 相似文献
18.
A. V. Ershov D. I. Tetelbaum I. A. Chugrov A. I. Mashin A. N. Mikhaylov A. V. Nezhdanov A. A. Ershov I. A. Karabanova 《Semiconductors》2011,45(6):731-737
The photoluminescence, infrared absorption, and Raman spectra of amorphous multilayered nanoperiodic a-SiO
x
/ZrO2 structures produced by vacuum evaporation and then annealed at different temperatures (500–1100°C) are studied. It is established
that the evolution of the optical properties with increasing annealing temperature is controlled by sequential transformation
of Si clusters formed in the SiO
x
layers from nonphase inclusions to amorphous clusters and then to nanocrystals. The finally formed nanocrystals are limited
in sizes by the thickness of the initial SiO
x
layers and by chemical reactions with ZrO2. 相似文献
19.
C. K. Egan P. Dabrowski Z. Klusek A. W. Brinkman 《Journal of Electronic Materials》2009,38(8):1528-1532
The effects of several ex vacuo methods used in the surface preparation of Cd1−x
Zn
x
Te (CZT) have been studied using noncontact atomic force microscopy, scanning tunneling microscopy, and scanning tunneling
spectroscopy. Preparation techniques include mechanical lapping, hydroplane bromine-methanol polishing, and in vacuo annealing. The morphology, electrical homogeneity, and local density of states (LDOS) have been studied for each preparation
method. Impurities and oxides quickly form on the surface after each preparation method. Annealing in ultrahigh vacuum causes
the surface electronic structure to become inhomogeneous whilst the LDOS suggests a compositional change from an oxide surface
to p-type CZT. 相似文献
20.
Y. Chen T. J. Zhu S. H. Yang S. N. Zhang W. Miao X. B. Zhao 《Journal of Electronic Materials》2010,39(9):1719-1723
A new preparation process combining melt spinning and hot pressing has been developed for the (Ag
x
SbTe
x/2+1.5)15(GeTe)85 (TAGS-85) system. Compared with samples prepared by the traditional air-quenching and hot-pressing method, electrical conductivity
and thermal conductivity are lowered. The thermoelectric performance of the TAGS-85 samples varied with changing Ag content
and reached the highest ZT of 1.48 when x was 0.8 for the melt-spun sample, compared with the maximum ZT of 1.36 for the air-quenched sample. The Seebeck coefficient of the melt-spun TAGS-85 alloys was improved, while both the
electrical conductivity and thermal conductivity were decreased. The net result of this process is to effectively enlarge
the temperature span of ZT > 1, which will benefit industrial application. 相似文献