共查询到20条相似文献,搜索用时 15 毫秒
1.
E. Dimakis E. Iliopoulos M. Kayambaki K. Tsagaraki A. Kostopoulos G. Konstantinidis A. Georgakilas 《Journal of Electronic Materials》2007,36(4):373-378
The molecular beam epitaxy of In-face InN (0001) epilayers with optimized surface morphology, structural quality, and electrical
properties was investigated. Namely, compact InN epilayers with atomically flat surfaces, grown in a step-flow mode, were
obtained using stoichiometric fluxes of In and N and substrate temperatures in the range from 400°C to 435°C. Typical values
for the electron concentration and the Hall mobility at 300 K were 4.3 × 1018 cm−3 and 1210 cm2/Vs, respectively. The growth mode of InN during the very first stage of the nucleation was investigated analytically, and
it was found that the growth proceeds through nucleation and fast coalescence of two-dimensional (2-D)–like InN islands. The
preceding conditions were used to grow an InN/GaN quantum well (QW) heterostructure, which exhibited well-defined interfaces.
Schottky contacts were successfully fabricated using a 15-nm GaN barrier enhancement cap layer. Capacitance-voltage measurements
revealed the confinement of electrons within the InN QW and demonstrated the capability to modulate the electron density within
an InN channel. The sheet concentration of the confined electrons (1.5 × 1013 cm−2) is similar to the calculated sheet polarization charge concentration (1.3 × 1013 cm−2) at the InN/GaN interface. However, electrons may also originate from ionized donors with a density of 8 × 1018 cm−3 within the InN layer. 相似文献
2.
Tamara B. Fehlberg Chad S. Gallinat Gilberto A. Umana-Membreno Gregor Koblmüller Brett D. Nener James S. Speck Giacinta Parish 《Journal of Electronic Materials》2008,37(5):593-596
A quantitative mobility spectrum analysis (QMSA) of multiple magnetic field data has been used to determine the transport
properties of bulk and surface electron species in InN films, grown by plasma-assisted molecular beam epitaxy (PAMBE) with
varying substrate temperatures and In/N flux ratios. While all films have similar bulk electron densities, ∼4 × 1017 cm−3, the highest mobility was obtained in the highest growth temperature film (3100 cm2/V s at 150 K), while In-rich growth also gave good mobility values even at a much lower growth temperature. The surface sheet
electron concentration increased with surface roughness, which increased with N-flux during growth. 相似文献
3.
Chih-Yang Chang Gou-Chung Chi Wei-Ming Wang Li-Chyong Chen Kuei-Hsien Chen F. Ren S. J. Pearton 《Journal of Electronic Materials》2006,35(4):738-743
The transport properties of single GaN and InN nanowires grown by thermal catalytic chemical vapor deposition were measured
as a function of temperature, annealing condition (for GaN) and length/square of radius ratio (for InN). The as-grown GaN
nanowires were insulating and exhibited n-type conductivity (n ≈ 2×1017 cm−3, mobility of 30 cm2/V s) after annealing at 700°C. A simple fabrication process for GaN nanowire field-effect transistors on Si substrates was
employed to measure the temperature dependence of resistance. The transport was dominated by tunneling in these annealed nanowires.
InN nanowires showed resistivity on the order of 4×10−4 Ω cm and the specific contact resistivity for unalloyed Pd/Ti/Pt/Au ohmic contacts was near 1.09×10−7 Ω cm2. For In N nanowires with diameters <100 nm, the total resistance did not increase linearly with length/square of radius ratio
but decreased exponentially, presumably due to more pronounced surface effect. The temperature dependence of resistance showed
a positive temperature coefficient and a functional form characteristic of metallic conduction in the InN nanowires. 相似文献
4.
A. Chandolu D. Y. Song M. E. Holtz I. Gherasoiu S. A. Nikishin A. Bernussi M. W. Holtz 《Journal of Electronic Materials》2009,38(4):557-562
We report studies of InN grown by plasma-assisted molecular beam epitaxy. GaN templates were first grown on sapphire substrates
followed by InN overgrown at 457°C to 487°C. Atomic force microscopy shows the best layers to exhibit step-flow growth mode
of the InN, with a root-mean-square roughness of 0.7 nm for the 2 μm × 2 μm scan and 1.4 nm for the 5 μm × 5 μm scan.␣Measurements of the terrace edges indicate a step height of 0.28 nm. Hall measurements at room temperature give mobilities
ranging from 1024 cm2/V s to 1904 cm2/V s and the electron concentrations are in the range of 5.9 × 1017 cm−3 to 4.2 × 1018 cm−3. Symmetric and asymmetric reflection x-ray diffraction measurements were performed to obtain lattice constants a␣and c. The corresponding hydrostatic and biaxial stresses are found to range from −0.08 GPa to −0.29 GPa, and −0.05 GPa to −0.32 GPa,
respectively. Low-temperature photoluminescence peak energies range from 0.67 eV to 0.70 eV, depending on residual biaxial
stress, hydrostatic pressure, and electron concentrations. The electron concentration dependence of the estimated Fermi level
is analyzed using Kane’s two-band model and conduction-band renormalization effects. 相似文献
5.
K. Kimura S. Miwa T. Yasuda L. H. Kuo A. Ohtake C. G. Jin K. Tanaka T. Yao 《Journal of Electronic Materials》1997,26(6):705-709
We have studied the p-type doping in ZnSe molecular beam epitaxial growth using a novel high-power (5 kW) radio frequency
(rf) plasma source. The effect of growth conditions such as the rf power, the Se/Zn flux ratio and the growth temperature
on p-ZnSe:N was investigated. The net acceptor concentration (NA—ND) of around 1 × 1018 cm−3 was reproducibly achieved. The activation ratio ((NA—ND)/[N]) of p-ZnSe:N with NA—ND of 1.2 × 1018 cm−3 was found to be as high as 60%, which is the highest value so far obtained for NA—ND ∼ 1018 cm−3. The 4.2K photoluminescence spectra of p-ZnSe:N grown under the optimized growth condition showed well-resolved deep donor-acceptor
pair emissions even with high NA—ND.
On leave from Sumitomo Electric Industry Ltd.
On leave from Sony Corp. 相似文献
6.
Zhonghai Yu S. L. Buczkowski M. C. Petcu N. C. Giles T. H. Myers M. Richards-Babb 《Journal of Electronic Materials》1996,25(8):1247-1253
Nitrogen doping in CdTe epilayers grown by photo-assisted molecular beam epitaxy was demonstrated using an rf plasma source.
The effect of the presence of atomic hydrogen during growth of undoped and nitrogen-doped CdTe was investigated. The layers
were characterized using photoluminescence spectros-copy (PL), Hall effect, secondary ion mass spectroscopy (SIMS), Fourier
transform infrared spectroscopy, and atomic force microscopy. PL confirmed the incorporation of nitrogen as acceptors. While
p-type carrier concentrations greater than 1018 cm−3 were easily obtained, SIMS measurements indicated that nitrogen was concentrated near the undoped-doped and epilayer-substrate
interfaces which complicates interpretation of activation efficiency. Hydrogen incorporation was found to be enhanced by the
presence of nitrogen. Infrared absorption measurements strongly suggested the formation of N-H complexes. Hall measurements
indicated that complexes are formed which are donor-like in nature. The presence of atomic hydrogen during growth radically
changed the low temperature photoluminescence in both undoped and nitrogen-doped layers. Exciton-related luminescence was
quenched at low temperature. Nitrogenrelated donor-acceptor pair luminescence was also absent from the N-doped hydrogenated
layers, consistent with complex formation. Copper (a cation-site acceptor) donor-acceptor pair luminescence appeared to be
enhanced by hydrogenation. 相似文献
7.
P. S. Nayar 《Journal of Electronic Materials》1982,11(6):967-977
An effective method of dopant incorporation in rf sputtered ZnO film is reported. The electrical, optical and structural properties
of zinc doped ZnO films are investigated. Electron mobility of∼10 cm2 /V-sec and electron concentration of∼1019 cm−3 have been measured at room temperature. X-ray diffraction data obtained on films prepared on Corning 7059 glass show (002)
peak, dominating. The high electrical conductivity and transmission makes ZnO films very attractive as a component for heterojunction
solar cells. 相似文献
8.
D. L. Partin L. Green D. T. Morelli J. Heremans B. K. Fuller C. M. Thrush 《Journal of Electronic Materials》1991,20(12):1109-1115
The growth and characterization of indium arsenide films grown on indium phosphide substrates by the metal organic chemical
vapor deposition (MOCVD) process is reported. Either ethyl dimethyl indium or trimethyl indium were found to be suitable in
combination with arsine as source compounds. The highest electron mobilities were observed in films nucleated at reduced growth
temperature. Scanning electron microscopy studies show that film nucleation at low temperature prevents thermal etch pits
from forming on the InP surface before growth proceeds at an elevated temperature. Electron mobilities as high as 21,000 cm2V−1 sec−1 at 300 K were thus obtained for a film only 3.4 μm thick. This mobility is significantly higher than was previously observed
in InAs films grown by MOCVD. From the depth dependence of transport properties, we find that in our films electrons are accumulated
near the air interface of the film, presumably by positive ions in the native oxide. The mobility is limited by electrons
scattering predominantly from ionized impurities at low temperature and from lattice vibrations and dislocations at high temperature.
However, scattering from dislocations is greatly reduced in the surface accumulation layer due to screening by a high density
of electrons. These dislocations arise from lattice mismatch and interface disorder at the film-substrate interface, preventing
these films from obtaining mobility values of bulk indium arsenide. 相似文献
9.
C. P. Kuo R. M. Cohen K. L. Fry G. B. Stringfellow 《Journal of Electronic Materials》1985,14(3):231-244
High quality GaxIn1−xAs, lattice matched to InP, has been reproducibly grown by organometallic vapor phase epitaxy using trimethylgallium (TMGa),
trimethylindium (TMIn), and AsH3 in an atmospheric pressure reactor with no observable adduct formation. For the first time, using TMIn, room temperature
electron mobilities of 104 cm2/Vs and 77 K mobilities greater than 4 × 104 cm2/Vs have beep obtained. Residual donor doping densities in the low 1015 cm−3 range have been routinely obtained. Material with excellent morphology has been grown from 540 to 670 C with the highest
quality material being obtained near 650 C. The 4 K photoluminescence (PL) peak due to carbon is not seen in the material
grown at higher temperatures; however, it increases dramatically as the growth temperature is lowered. This increased carbon
incorporation leads to a sharp drop in the electron mobility, which exhibits a T−0.5 behavior between 77 and 300 K. With optimum growth conditions, 4 K PL halfwidths of 4–5 meV are commonly observed. This high
quality material is characterized by x-ray diffraction, PL, and Hall mobility measurements. Carbon and other impurity incorporation
as a function of the growth parameters will be described. 相似文献
10.
T. Akagi K. Kosaka S. Harui D. Muto H. Naoi T. Araki Y. Nanishi 《Journal of Electronic Materials》2008,37(5):603-606
The correlation between threading dislocations (TDs) and nonradiative recombination centers in InN films was investigated
by infrared cathodoluminescence (CL). Samples were grown on nitridated (0001) sapphire substrates with a low-temperature-grown
InN buffer layer by radio frequency molecular-beam epitaxy (RF-MBE). Panchromatic CL images of the InN films showed a high
density of dark spots in a range of 108 cm−2 to 109 cm−2. The sample with a higher density of TDs had a higher density of CL dark spots. A depth-dependent CL measurement confirmed
that CL dark spots aligned almost vertically in the film like TDs. Reasonable correlation between TDs and the nonradiative
regions was also observed by a cross-sectional CL image of the InN film regrown on a microfaceted InN template, in which the
TD density was dramatically reduced in part. These results suggest that threading dislocations act as nonradiative recombination
centers in InN. 相似文献
11.
Electrical and optical properties of InP grown by low-pressure metalorganic chemical vapor deposition using triethylindium
(TEI) and phosphine (PH3) are described. It was found that the net ionized impurity concentration shows a monotonic decrease as the PH3/TEI ratio increases. Similarly, the electron mobility and the photoluminescent intensity increases with the PH3/TEI ratio. The effect of growth temperature has also been investigated in the range from 500 to 650°C. For a variety of PH3/TEI ratios, the optimal growth temperature is in the range of 550×600éC. In terms of impurities, the dominant shallow acceptors
are Zn and possibly C, and the most common deep acceptor is Mn. The best material obtained shows a net electron concentration
of 1 × 1015 cm−3 with an associated 77K electron mobility of 41,000 cm2 /Vsec, implying that the total ionized,impurity concentration is in the range of 3'4 □ 1015 cm−3 相似文献
12.
Continued improvement in GaAs/AlGaAs device technology requires higher doping levels, both to reduce parasitics such as source
resistances, and to enhance speed in devices such as the heterostructure bipolar transistor (HBT). In this paper we will discuss
doping issues which are critical to high speed performance. In particular, we will focus on doping of GaAs and AIGaAs using
carbon as the acceptor and Sn as the donor. Due to the unique growth chemistry of metalorganic molecular beam epitaxy (MOMBE),
both of these impurities can be used to achieve high doping levels when introduced from gaseous sources such as trimethylgallium
(TMG) or tetraethyltin (TESn). Comparison of SIMS and Hall measurements show that both elements give excellent electrical
activation to 1.5 × 1019 cm3 for Sn and 5 × 1020 cm−3 for C. More importantly, we have found that both impurities canbe used to achieve high quality junctions, indicating that
little or no diffusion or segregation is occurring during growth. Because of the excellent incorporation behavior of these
dopants, we have been able to fabricate a wide range of devices including field effect transistors (FETs), high electron mobility
transistors (HEMTs), and Pnp HBTs whose performance equals or exceeds that of similar devices grown by other techniques. In
addition to these results, we will briefly discuss the key differences in growth kinetics which allow such abruptness and
high doping levels to be achieved more readily in MOMBE than in other growth techniques. 相似文献
13.
A. E. Wickenden D. D. Koleske R. L. Henry R. J. Gorman M. E. Twigg M. Fatemi J. A. Freitas Jr. W. J. Moore 《Journal of Electronic Materials》2000,29(1):21-26
Growth pressure has a dramatic influence on the grain size, transport characteristics, optical recombination processes, and
alloy composition of GaN and AlGaN films. We report on systematic studies which have been performed in a close spaced showerhead
reactor and a vertical quartz tube reactor, which demonstrate increased grain size with increased growth pressure. Data suggesting
the compensating nature of grain boundaries in GaN films is presented, and the impact of grain size on high mobility silicon-doped
GaN and highly resistive unintentionally doped GaN films is discussed. We detail the influence of pressure on AlGaN film growth,
and show how AlGaN must be grown at pressures which are lower than those used for the growth of optimized GaN films. By controlling
growth pressure, we have grown high electron mobility transistor (HEMT) device structures having highly resistive (105 Ω-cm) isolation layers, room temperature sheet carrier concentrations of 1.2×1013 cm−2 and mobilities of 1500 cm2/Vs, and reduced trapping effects in fabricated devices. 相似文献
14.
We report a study of N incorporation into InP using a radio frequency (rf) N plasma source. Very streaky reflection high-energy
electron diffraction patterns are observed for InNxP1−x (x <1%) grown on InP, indicating layer-by-layer growth of the film. The sharp x-ray diffraction peak and the clear Pendelloesung
fringes in the high-resolution x-ray rocking curves reveal the high crystalline quality and uniformity of the film. They also
suggest the smoothness of the interface between InP and InNxP1−xand of the surface of the InNxP1−x layer. This is further confirmed by scanning electron microscopy on these samples, where featureless surface is obtained.
The formation of an InNP alloy is confirmed by x-ray θ-2θ diffraction measurement where no phase separation is observed. Different
ways to increase the N composition in InNP were explored. At a fixed N2 flow-rate fraction, lowering the growth temperature increases the N composition in InNP. Raising the rf power or using a
larger beam exit aperture will also increase the N incorporation as a result of the availability of more active N species. 相似文献
15.
C.C. Huang R.W. Chuang S.J. Chang J.C. Lin Y.C. Cheng W.J. Lin 《Journal of Electronic Materials》2008,37(8):1054-1057
We report the growth of InN by metalorganic chemical vapor deposition on Si(111) substrates. It was found that the sharpest
InN(002) x-ray diffraction peak could be achieved from the sample prepared on a complex buffer layer that consists of a low-temperature
AlN, a graded Al
x
Ga1−x
N (x = 1 → 0), and a high-temperature GaN. The resultant mobility of 275 cm2/V s thus obtained was 75% larger than that of the InN prepared on a single LT-AlN buffer layer only. 相似文献
16.
A wide range of samples of both n-type and p-type GaxIn1-xAsyP1-y on InP has been grown by LPE with carrier concentrations in the low 1016cm−3range. The electron mobility (μe) at room temperature decreased from about 4000 cm2V−1s−1 at y = 0 and passed through a shallow minimum near y = 0.25. At high y values, μe rose steeply, reaching 11 000 cm2V−1s−1 at the ternary boundary. In the p-type material the hole mobility (μp) varied from 140 cm V−1s−1 in InP, passed through a minimum of about 70 cm2V−1s−1 near y = 0.5 and then increased swiftly towards the ternary boundary. The temperature dependence of both μe and μp suggested the presence of alloy or space-charge scattering. In order to distinguish between these two mechanisms the pressure
coefficient of the direct band-gap dEo/dP was measured as a function of y by observing the movement with pressure of the photoconductive edge. From dEo/dP the pressure variation of the effective mass was deduced. By measuring the change in electron and hole mobilities with
pressure, it was then possible to establish that alloy scattering rather than space-charge scattering was occurring. From
the composition dependence of the alloy scattering potentials for electrons and holes predictions have been made of the variation
of μe and μP with temperature, pressure and dopant Presently a Nuffield Science Fellow concentration. At room temperature a maximum electron
mobility of about 11,200 cm2V−1 s−1 is indicated.
Presently a Nuffield Science Fellow 相似文献
17.
Z. Cai S. Garzon M.V.S. Chandrashekhar R.A. Webb G. Koley 《Journal of Electronic Materials》2008,37(5):585-592
We report on the growth of high-quality InN nanowires by the vapor–liquid–solid mechanism at rates of up to 30 μm/h. Smooth and horizontal nanowire growth has been achieved only with nanoscale catalyst patterns, while large-area catalyst
coverage resulted in uncontrolled and three-dimensional growth. The InN nanowires grow along the [110] direction with diameters
of 20 to 60 nm and lengths of 5 to 15 μm. The nanowires bend spontaneously or get deflected from other nanowires at angles that are multiples of 30°, forming nanonetworks.
The gate-bias-dependent mobility of the charge carriers ranges from 55 cm2/V s to 220 cm2/V s, and their concentration is ∼1018 cm−3. 相似文献
18.
David Pritchett Walter Henderson Shawn D. Burnham W. Alan Doolittle 《Journal of Electronic Materials》2006,35(4):562-567
The surface reaction byproducts during the growth of GaN films via metal organic molecular beam epitaxy (MOMBE) were investigated
as a means to optimize material properties. Ethylene and ethane were identified as the dominant surface reaction hydrocarbon
byproducts, averaging 27.63% and 7.15% of the total gas content present during growth. Intense ultraviolet (UV) photoexcitation
during growth was found to significantly increase the abundance of ethylene and ethane while reducing the presence of H2 and N2. At 920°C, UV excitation was shown to enhance growth rate and crystalline quality while reducing carbon incorporation. Over
a limited growth condition range, a 4.5×1019−3.4×1020 cm−3 variation in carbon incorporation was achieved at constant high vacuum. Coupled with growth rate gains, UV excitation yielded
films with ∼58% less integrated carbon content. Structural material property variations are reported for various ammonia flows
and growth temperatures. The results suggest that high carbon incorporation can be achieved and regulated during MOMBE growth
and that in-situ optimization through hydrocarbon analysis may provide further enhancement in the allowable carbon concentration
range. 相似文献
19.
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
20.
Kazuhiko Suzuki S. Seto A. Iwata M. Bingo T. Sawada K. Imai 《Journal of Electronic Materials》2000,29(6):704-707
The electron drift mobility of undoped Cd0.9Zn0.1Te grown by high-pressure Bridgman method is measured by a time-of-flight technique. The sample shows a room temperature mobility
and mobility lifetime product of 950 cm2/Vs and 1.6 × 10−4cm2/V, respectively. The mobility increases monotonically with decreasing temperature to 3000 cm2/Vs at 100 K. The dominant scattering mechanism for the electron transport is discussed by comparing with the theoretical
mobility obtained by iterative solution of the Boltzmann equation. 相似文献