共查询到20条相似文献,搜索用时 15 毫秒
1.
Guanghan Fan J Iwan Davies Nicholas Maung Maxwell J Parrott John O Williams 《Journal of Electronic Materials》1986,15(4):251-255
Epitaxial layers of ZnSe ranging in thickness from 5μm to 30 μm have been grown on GaAs (100) substrates over the temperature
range 240° C to 340° C by atmospheric pressure MOVPE employing dimethylzinc and hydrogen selenide. An optimum growth temperature
of 280 ± 5° C has been identified and when grown at this temperature the ZnSe epitaxial layers exhibit low resistivity (ρ298
K ≤ 10 ohm · cm), a low compensation ratio (θ298
K = 0.27), a carrier mobility (μ298
K) of 250 ±10 cm2V-1s-1) and aren-type (n
298
K = 8.0 × 1014 cm-3). The ratio of photoluminescence intensity measured at 298K and at 12 K is high (104) and is dominated by a sharp emission due to excitons bound to neutral donors at 2.7956 eV. Mass spectrometric investigations
of the chemical reactions occurring inside the reactor in the presence of the GaAs substrate indicate significant surface-controlled
reactivity in the region of 280° C. 相似文献
2.
GaAs was grown by molecular beam epitaxy (MBE) and ion-assisted MBE on Si(100) substrates. Three-dimensional (3D) island nucleation,
observed during MBE growth, was eliminated during ion-assisted MBE when the ion energyE was >25 eV and the product ofE and the current densityJ was ≈6-12 eV mA/cm2. IncreasingEJ to ≈15 eV mA/ cm2 resulted in excessive ion damage. Decreasing the substrate temperature from 280 to 580° C during ion-assisted MBE yielded
a slight decrease in surface roughness, and flatter surfaces were obtained for lower As4/Ga flux ratios. The suppression of 3D island nucleation led to an improvement in the crystalline perfection of thicker GaAs
films. For example, the x-ray diffraction rocking-curve full-width-at-half-maximum values for 0.5 μm thick films grown at
380° C decreased from 1700 arcsec to 1350 arcsec when ion irradiation was used during nucleation. IAMBE allowed nucleation
of thin, relatively flat-surfaced GaAs films even at 580° C, resulting in FWHM values of 1850 arcsec for 0.14 /μm thick films. 相似文献
3.
Shih-Yuan Lin Ying-Chung Chen Chih-Ming Wang Kuo-Sheng Kao Chih-Yuan Chan 《Journal of Electronic Materials》2009,38(3):453-459
Calcium copper titanium oxide (CaCu3Ti4O12, abbreviated to CCTO) films were deposited on Pt/Ti/SiO2/Si substrates at room temperature (RT) by radiofrequency magnetron sputtering. As-deposited CCTO films were treated by rapid
thermal annealing (RTA) at various temperatures and in various atmospheres. X-ray diffraction patterns and scanning electron
microscope (SEM) images demonstrated that the crystalline structures and surface morphologies of CCTO thin films were sensitive
to the annealing temperature and ambient atmosphere. Polycrystalline CCTO films could be obtained when the annealing temperature
was 700°C in air, and the grain size increased signifi- cantly with annealing in O2. The 0.8-μm CCTO thin film that was deposited at RT for 2 h and then annealed at 700°C in O2 exhibited a high dielectric constant (ε′) of 410, a dielectric loss (tan δ) of 0.17 (at 10 kHz), and a leakage current density (J) of 1.28 × 10−5 A/cm2 (at 25 kV/cm). 相似文献
4.
Thin films of the semiconducting compound Mg2Ge were deposited by magnetron cosputtering from source targets of high-purity Mg and Ge onto glass substrates at temperatures
T
s = 300°C to 700°C. X-ray diffraction shows that the Mg2Ge compound begins to form at a substrate temperature T
s ≈ 300°C. Films deposited at T
s = 400°C to 600°C are single-phase Mg2Ge and have strong x-ray peaks. At higher T
s the films tend to be dominated by a Ge-rich phase primarily due to the loss of magnesium vapor from the condensing film.␣At
optimum deposition temperatures, 550°C to 600°C, films have an electrical conductivity σ
600 K = 20 Ω−1 cm−1 to 40 Ω−1 cm−1 and a Seebeck coefficient α = 300 μV K−1 to 450 μV K−1 over a broad temperature range of 200 K to 600 K. 相似文献
5.
T. Lien Tran Fariba Hatami W. Ted Masselink Vas P. Kunets G.J. Salamo 《Journal of Electronic Materials》2008,37(12):1799-1805
We describe the epitaxial growth of InSb films on both Si (001) and GaAs (100) substrates using molecular-beam epitaxy and
discuss the structural and electrical properties of the resulting films. The complete 2 μm InSb films on GaAs (001) were grown
at temperatures between 340°C and 420°C and with an Sb/In flux ratio of approximately 5 and a growth rate of 0.2 nm/s. The
films were characterized in terms of background electron concentration, mobility, and x-ray rocking curve width. Our best
results were for a growth temperature of 350°C, resulting in room-temperature mobility of 41,000 cm2/V s. For the growth of InSb on Si, vicinal Si(001) substrates offcut by 4° toward (110) were used. We investigated growth
temperatures between 340°C and 430°C for growth on Si(001). In contrast to growth on GaAs, the best results were achieved
at the high end of the range of T
S = C, resulting in a mobility of 26,100 cm2/V s for a 2 μm film. We also studied the growth and properties of InSb:Mn films on GaAs with Mn content below 1%. Our results
showed the presence of ferromagnetic ordering in the samples, opening a new direction in the diluted magnetic semiconductors. 相似文献
6.
K. Iwata H. Asahi T. Ogura J. Sumino S. Gonda A. Ohki Y. Kawaguchi T. Matsuoka 《Journal of Electronic Materials》1996,25(5):637-641
To solve the difficulty of achieving low resistance ohmic contact to p-type ZnSe, the use of an intermediate p-type InAlP
layer to p-type ZnSe as a valence band offset reduction layer is studied by gas source molecular beam epitaxy. It is found
that hole concentrations as high as 2 × 1018 cm−3 are easily obtained for p-type InAlP layers grown on GaAs even at low temperature of 350°C, although a higher Be cell temperature
is required than that for a 500°C grown p-type InAlP due to the decreased electrical activity of Be in InAlP. Despite the
very high Be concentrations, the Be precipitation/segregation is not observed. It was difficult to obtain the same hole concentration
of InAlP layers grown on ZnSe as that on GaAs. However, the insertion of only several monolayers of GaAs between ZnSe and
InAlP makes it possible to avoid faceting growth of InAlP and to improve the electrical properties of Be-doped InAlP grown
on ZnSe. These results suggest that the Be-doped InAlP layer can be used as an intermediate layer to form the low resistance
ohmic contact to p-type ZnSe. 相似文献
7.
We have performed a preliminary investigation into the use of ZnSe bulk crystals fabricated by Sumitomo Electric Industries,
Ltd. as substrates for the epitaxial1 deposition of ZnSe-based materials and light emitting devices. A low temperature (<380
°C)in- situ cleaning process has been developed for the (100) oriented ZnSe wafers involving the use of a remotely generated atomic hydrogen
beam. The process produces a (1 × 1) atomically smooth ZnSe surface which is highly suitable for epitaxy. Hall-effect measurements
performed on nitrogen-doped ptype ZnSe/S.I. ZnSe epilayers have revealed free-hole concentrations in the homoepitaxial material
as high as 2.1 × 1017cm−3, so far, with room temperature and 77Khole mobility values of 20 and 100 cm2V
su−1
ins/su−1
, respectively. Finally, green light emitting diodes have been grown on the ZnSe wafers having Cd0.2Zn0.8Se/ ZnSe multiple quantum well active regions which have exhibited electroluminescence peak linewidths around 9.9 nm at room
temperature. 相似文献
8.
N. A. Bert A. A. Suvorova V. V. Chaldyshev Yu. G. Musikhin V. V. Preobrazhenskii M. A. Putyato B. R. Semyagin R. Werner 《Semiconductors》1998,32(7):683-688
Transmission electron microscopy is used to study the microstructure of indium δ layers in GaAs(001) grown by molecular beam epitaxy at low temperature (200 °C). This material, referred to as LT-GaAs, contains a high concentration (≈1020 cm−3) of point defects. It is established that when the material is δ-doped with indium to levels equivalent to 0.5 or 1 monolayer (ML), the roughness of the growth surface leads to the formation
of InAs islands with characteristic lateral dimensions <10 nm, which are distributed primarily within four adjacent atomic
layers, i.e., the thickness of the indium-containing layer is 1.12 nm. Subsequent annealing, even at relatively low temperatures,
leads to significant broadening of the indium-containing layers due to the interdiffusion of In and Ga, which is enhanced
by the presence of a high concentration of point defects, particularly V
Ga, in LT-GaAs. By measuring the thickness of indium-containing layers annealed at various temperatures, the interdiffusion coefficient
is determined to be D
In-Ga=5.1×10−12 exp(−1.08 eV/kT) cm2/s, which is more than an order of magnitude larger than D
In-Ga for stoichiometric GaAs at 700 °C.
Fiz. Tekh. Poluprovodn. 32, 769–774 (July 1998) 相似文献
9.
Tianbao Chen Ping Fan Zhuanghao Zheng Dongping Zhang Xingmin Cai Guangxing Liang Zhaokun Cai 《Journal of Electronic Materials》2012,41(4):679-683
Antimony and tellurium were deposited on BK7 glass using direct-current magnetron and radiofrequency magnetron cosputtering.
Antimony telluride thermoelectric thin films were synthesized with a heated substrate. The effects of substrate temperature
on the structure, surface morphology, and thermoelectric properties of the thin films were investigated. X-ray diffraction
patterns revealed that the thin films were well crystallized. c-Axis preferred orientation was observed in thin films deposited above 250°C. Scanning electron microscopy images showed hexagonal
crystallites and crystal grains of around 500 nm in thin film fabricated at 250°C. Energy-dispersive spectroscopy indicated
that a temperature of 250°C resulted in stoichiometric Sb2Te3. Sb2Te3 thin film deposited at room temperature exhibited the maximum Seebeck coefficient of 190 μV/K and the lowest power factor (PF), S
2
σ, of 8.75 × 10−5 W/mK2. When the substrate temperature was 250°C, the PF increased to its highest value of 3.26 × 10−3 W/mK2. The electrical conductivity and Seebeck coefficient of the thin film were 2.66 × 105 S/m and 113 μV/K, respectively. 相似文献
10.
Baumann J. A. Michel C. Marek H. Serreze H. B. Schachter R. 《Journal of Electronic Materials》1990,19(4):363-366
The performance characteristics of epitaxial structures suitable for optoelectronic and electronic devices were investigated.
These were fabricated by MOVPE using tertiary-butylarsine, a non-hydride arsenic source. Minority carrier diffusion lengths
of 5μm at 3 × 1018/cm3 and 2μm at 2 × 1019/cm3 were achieved inp-type GaAs. Recombination velocities at the GaAs/AlGaAs interface are reduced to 1 × 103 cm/sec by processing under appropriate conditions. Electron mobilities of 4000 cm2/V-sec inn-type (2 × 1017/cm3) layers resulted in transconductances of 120 mS/mm in 1.5μm gate depletion mode MESFETs. The above values are comparable to those obtained with arsine in this work and others reported
in the literature. 相似文献
11.
Dong H. K. Li N. Y. Tu C. W. Geva M. Mitchel W. C. 《Journal of Electronic Materials》1995,24(2):69-74
The growth of GaAs by chemical beam epitaxy using triethylgallium and trisdimethylaminoarsenic has been studied. Reflection
high-energy electron diffraction (RHEED) measurements were used to investigate the growth behavior of GaAs over a wide temperature
range of 300–550°C. Both group III- and group Vinduced RHEED intensity oscillations were observed, and actual V/III incorporation
ratios on the substrate surface were established. Thick GaAs epitaxial layers (2–3 μm) were grown at different substrate temperatures
and V/III ratios, and were characterized by the standard van der Pauw-Hall effect measurement and secondary ion mass spectroscopy
analysis. The samples grown at substrate temperatures above 490°C showed n-type conduction, while those grown at substrate
temperatures below 480°C showed p-type conduction. At a substrate temperature between 490 and 510°C and a V/III ratio of about
1.6, the unintentional doping concentration is n ∼2 × 1015 cm−3 with an electron mobility of 5700 cm2/V·s at 300K and 40000 cm2/V·s at 77K. 相似文献
12.
M. W. Wanlass T. J. Coutts J. S. Ward K. A. Emery G. S. Horner 《Journal of Electronic Materials》1991,20(12):1019-1024
High-efficiency, thin-film InP solar cells grown heteroepitaxially on GaAs and Si single-crystal bulk substrates are being
developed as a means of eliminating the problems associated with using single-crystal InP substrates (e.g., high cost, fragility, high mass density and low thermal conductivity). A novel device structure employing a compositionally
graded Ga
x
In1−x
As layer (∼8 μm thick) between the bulk substrate and the InP cell layers is used to reduce the dislocation density and improve
the minority carrier properties in the InP. The structures are grown in a continuous sequence of steps using computer-controlled
atmospheric-pressure metalorganic vapor-phase epitaxy (AP-MOVPE). Dislocation densities as low as 3×107 cm−2 and minority carrier lifetimes as high as 3.3 ns are achieved in the InP layers with this method using both GaAs or Si substrates.
Structures prepared in this fashion are also completely free of microcracks. These results represent a substantial improvement
in InP layer quality when compared to heteroepitaxial InP prepared using conventional techniques such as thermally cycled
growth and post-growth annealing. The present work is concerned with the fabrication and characterization of thin-film InP
solar cells designed for operation at high solar concentration (∼100 suns) which have been prepared from similar device structures
grown on GaAs substrates. The cell performance is characterized as a function of the air mass zero (AM0) solar concentration
ratio (1–100 suns) and operating temperature (25°–80° C). From these data, the temperature coefficients of the cell performance
parameters are derived as a function of the concentration ratio. Under concentration, the cells exhibit a dramatic increase
in efficiency and an improved temperature coefficient of efficiency. At 25° C, a peak conversion efficiency of 18.9% (71.8
suns, AM0 spectrum) is reported. At 80° C, the peak AM0 efficiency is 15.7% at 75.6 suns. These are the highest efficiencies
yet reported for InP heteroepitaxial cells. Approaches for further improving the cell performance are discussed. 相似文献
13.
H. Udono K. Nakamori Y. Takahashi Y. Ujiie I. J. Ohsugi T. Iida 《Journal of Electronic Materials》2011,40(5):1165-1170
We have investigated the crystal growth of single-phase MnSi1.75−x
by a temperature gradient solution growth (TGSG) method using Ga and Sn as solvents and MnSi1.7 alloy as the solute, and measured the thermoelectric properties of the resulting crystals. Single-phase Mn11Si19 and Mn4Si7 crystals were grown successfully using Ga and Sn as solvents, respectively. The typical size of a grown ingot of Mn11Si19 was 2 mm to 4 mm in thickness and 12 mm in diameter, whereas Mn4Si7 had polyhedral shape with dimensions in the range of several millimeters. The single-phase Mn11Si19 has good electrical conduction (ρ = 0.89 × 10−3 Ω cm to 1.09 × 10−3 Ω cm) compared with melt-grown multiphase higher-manganese silicide (HMS) crystals. The Seebeck coefficient, power factor,
and thermal conductivity were 77 μV K−1 to 85 μV K−1, 6.7 μW cm−1 K−2 to 7.2 μW cm−1 K−2, and 0.032 W cm−1 K−1, respectively, at 300 K. 相似文献
14.
X. G. Zhang S. Kalisetty J. Robinson G. Zhao D. W. Parent J. E. Ayers F. C. Jain 《Journal of Electronic Materials》1997,26(6):697-704
ZnSySe1−yZnSe/GaAs (001) heterostructures have been grown by photoassisted metalorganic vapor phase epitaxy, using the sources dimethylzinc,
dimethylselenium, diethylsulfur, and irradiation by a Hg arc lamp. The solid phase composition vs gas phase composition characteristics
have been determined for ZnSyySe1−y grown with different mole fractions of dimethylselenium and different temperatures. Although the growth is not mass-transport
controlled with respect to the column VI precursors, the solid phase composition vs gas phase composition characteristics
are sufficiently gradual so that good compositional control and lattice matching to GaAs substrates can be readily achieved
by photoassisted growth in the temperature range 360°C ≤ T ≤ 400°C. ZnSe/GaAs (001) single heterostructures were grown by
a two-step process with ZnSe thicknesses in the range from 54 nm to 776 nm. Based on 004 x-ray rocking curve full width at
half maximums (FWHMs), we have determined that the critical layer thickness is hc ≤200 nm. Using the classical method involving strain, lattice relaxation is undetectable in layers thinner than 270 nm for
the growth conditions used here. Therefore, the rocking curve FWHM is a more sensitive indicator of lattice relaxation than
the residual strain. For ZnSySe1−y layers grown on ZnSe buffers at 400°C, the measured dislocation density-thickness product Dh increases monotonically with
the room temperature mismatch. Lower values of the Dh product are obtained for epitaxy on 135 nm buffers compared to the case
of 270 nm buffers. This difference is due to the fact that the 135 nm ZnSe buffers are pseudomorphic as deposited. For ZnSySe1−y layers grown on 135 nm ZnSe buffers at 360°C, the minimum dislocation density corresponds approximately to room-temperature
lattice matching (y ∼ 5.9%), rather than growth temperature lattice matching (y ∼ 7.6%). Epitaxial layers with lower dislocation
densities demonstrated superior optical quality, as judged by the near-band edge/deep level emission peak intensity ratio
and the near band edge absolute peak intensity from 300K photoluminescence measurements. 相似文献
15.
B. N. Pantha R. Dahal J. Li J. Y. Lin H. X. Jiang G. Pomrenke 《Journal of Electronic Materials》2009,38(7):1132-1135
We report on the experimental investigation of the potential of InGaN alloys as thermoelectric (TE) materials. We have grown
undoped and Si-doped In0.3Ga0.7N alloys by metalorganic chemical vapor deposition and measured the Seebeck coefficient and electrical conductivity of the
grown films with the aim of maximizing the power factor (P). It was found that P decreases as electron concentration (n) increases. The maximum value for P was found to be 7.3 × 10−4 W/m K2 at 750 K in an undoped sample with corresponding values of Seebeck coefficient and electrical conductivity of 280 μV/K and 93␣(Ω cm)−1, respectively. Further enhancement in P is expected by improving the InGaN material quality and conductivity control by reducing background electron concentration. 相似文献
16.
Shuang Fu Ke-Jia Qian Shi-Jin Ding David Wei Zhang 《Journal of Electronic Materials》2011,40(10):2139-2146
Ultralow-dielectric-constant (k) porous SiCOH films have been prepared using 1,2-bis(triethoxysilyl)ethane, triethoxymethylsilane, and a poly(ethylene oxide)–poly(propylene
oxide)–poly(ethylene oxide) triblock copolymer template by means of spin-coating. The resulting films were characterized by
cross-section scanning electron microscopy, small-angle x-ray diffraction, atomic force microscopy, Fourier-transform infrared
spectroscopy, nanomechanical testing, and electrical measurements. Thermal treatment at 350°C for 2 h resulted in the formation
of ultralow-k films with k of ∼2.0, leakage current density of 3 × 10−8 A/cm2 at 1 MV/cm, reduced modulus (E
r) of ∼4.05 GPa, and hardness (H) of ∼0.32 GPa. After annealing between 400°C and 500°C for 30 min, the resulting films showed fluctuant k values of 1.85 to 2.22 and leakage current densities of 3.7 × 10−7 A/cm2 to 3 × 10−8 A/cm2 at 0.8 MV/cm, likely due to the change of the film microstructure. Compared with 350°C annealing, higher-temperature annealing
can improve the mechanical strength of the ultralow-k film, i.e., E
r ≈ 5 GPa and H ≈ 0.56 GPa after 500°C annealing. 相似文献
17.
Many optoelectronic devices require contacts top-doped epitaxial layers. To achieve low contact resistance, the semiconductor has to be doped to high levels. Thep-dopants most commonly used are Be, Mg, and Zn. The contacts were formed by the sequential e-beam evaporation of 10 nm Pd,
≤5 nm Zn, 20 nm Pd and 40 nm Au layers onto a 0.2 μm thick Be-doped (5 × 1018 cm) GaAs layer grown by MBE. The minimum contact resistance of 0.04Ω-mm (≤1 × 10−7
Ω-cm2), as measured using the transmission line method, was obtained for contacts annealed at 500° C for 30s. These are the lowest
contact resistance values reported to date for alloyed contacts top-GaAs. 相似文献
18.
Boyko V. M. Verevkin S. S. Kolin N. G. Korulin A. V. Merkurisov D. I. Polyakov A. Y. Chevychelov V. A. 《Semiconductors》2011,45(1):134-140
Effect of irradiation with high reactor-neutron fluences (Φ = 1.5 × 1017-8 × 1019 cm−2) and subsequent heat treatments in the temperature range 100–1000°C on the electrical properties and lattice constant of
epitaxial GaN layers grown on an Al2O3 substrate is considered. It is shown that, with the neutron fluence increasing to (1–2) × 1018 cm−2, the resistivity of the material grows to values of about 1010 Ω cm because of the formation of radiation defects, and, with the fluence raised further, the resistivity passes through
a maximum and then decreases to 2 × 106 Ω cm at 300 K, which is accounted for by the appearance of a hopping conductivity via deep defects in the overlapping outer
parts of disordered regions. With the neutron fluence raised to 8 × 1019 cm−2, the lattice constant c increases by 0.38% at a nearly unchanged parameter a. Heat treatment of irradiated samples at temperatures as high as 1000°C does not fully restore the lattice constant and the
electrical parameters of the material. 相似文献
19.
We report deposition of (GaAs)1_x(Ge2)x on GaAs substrates over the entire alloy range. Growth was performed by metalorganic chemical vapor deposition at temperatures
of 675 to 750°C, at 50 and 760 Torr, using trimethylgallium, arsine, and germane at rates of 2–10 μ/h. Extrinsic doping was
achieved using silane and dimethylzinc in hydrogen. Characterization methods include double-crystal x-ray rocking curve analysis,
Auger electron spectroscopy, 5K photoluminescence, optical transmission spectra, Hall-effect, and Polaron profiling. Results
achieved include an x-ray rocking curve full-width at half maximum as narrow as 12 arc-s, Auger compositions spanning the
alloy range from x = 0.03 to x = 0.94, specular surface morphologies, and 5K photoluminescence to wavelengths as long as 1620
nm. Undoped films are n type, with n ≈ 1 × 1017 cm−3. Extrinsic doping with silane and dimethylzinc have resulted in films which are n type (1017 to 1018 cnr−3) or p type (5 × 1018 to 1 × 1020 cm−3). Mobilities are generally ≈ 50 cm2/V-s and 500 cm2/V-s, for p and n films, respectively. 相似文献
20.
Contact technology for GaAs involves optimizing such factors as contact resistance or Schottky barrier height, alloy cycle
conditions, thermal ageing, adhesion, and ease of high resolution processing. Minority carrier properties may be significantly
degraded by in-diffusing contact metals. At typical alloying conditions of 10 sec at 500° C, Ni diffuses at least 10 μm and
reduces the hole diffusion length (Lp) in vapor phase epitaxial GaAs from 4.4 to 1.7 ym. At 600°C, Lp becomes 1.0 μm. Other metals, such as Fe, Pt, and Cr, significantly improve Lp in VPE GaAs. Lp increases from 3.0 to 5.0 μm for an Fe diffusion of 5 minutes at 500°C. These improvements may be due to interaction of in-diffused
Fe with recombination centers, such as Ga vacancy complexes or Ni. Fe causes increases in minority carrier diffusion lengths
also in n and p type ingot GaAs, though 800 – 900°C diffusions are required and at these temperatures the doping is significantly
changed by Fe acceptors. 相似文献