共查询到20条相似文献,搜索用时 15 毫秒
1.
C. H. Grein J. W. Garland S. Sivananthan P. S. Wijewarnasuriya F. Aqariden M. Fuchs 《Journal of Electronic Materials》1999,28(6):789-792
The p-type doping of Hg1−xCdxTe (MCT) has proven to be a significant challenge in present day MCT-based detector technology. One of the most promising
acceptor candidates, arsenic, behaves as an amphoteric dopant which can be activated as an acceptor during Hg-rich, low temperature
annealing of as-grown molecular beam epitaxy (MBE) samples. This study focuses on developing an understanding of the microscopic
behavior of arsenic incorporation during MBE growth. In particular, the question of whether arsenic incorporates as individual
As atoms, as As2 dimers, or as As4 tetramers is addressed for MBE growth with an As4 source. A quasithermodynamical model is employed to describe the MCT growth and As incorporation, with parameters fitted
to an extensive database of samples grown at the Microphysics Laboratory. The best fits for growth temperatures between 175
and 185°C are obtained for arsenic incorporation as As4 or possibly as As4 clusters, with lower probabilities for As2 and individual As atoms. Based on these results, we investigate the relaxed atomic configurations of As4 and As2 in bulk HgTe by ab initio total energy calculations. The calculations are performed in the pseudopotential density-functional framework within the
local density approximation, employing supercells with periodic boundary conditions. The lattice distortions due to As4 and As2 in bulk HgTe are predicted to be modest due to the small size of these arsenic clusters. 相似文献
2.
L. K. Bera S. K. Ray D. K. Nayak N. Usami Y. Shiraki C. K. Maiti 《Journal of Electronic Materials》1999,28(2):98-104
Gas source molecular beam epitaxy has been employed for the growth of a high quality strained-Si layer on a completely relaxed
step-graded Si1−xGex buffer layer. As-grown strained-Si layers have been characterized using secondary ion mass spectroscopy, Rutherford backscattering
spectroscopy, atomic force microscopy, and spectroscopic ellipsometry for the determination of composition, thickness, crystalline
quality, and surface roughness. Heterojunction conduction and valence band offsets (ΔEc, ΔEυ) of strained-Si/SiGe heterostructure have been determined from measured threshold voltages of a strained-Si channel p-metal
oxide semiconductor field effect transistor (MOSFET) fabricated using grown films. MOS capacitance-voltage profiling has been
employed for the extraction of strained-Si layer thickness and apparent doping profile in the device. 相似文献
3.
Jiaqi Wei Kumsong Kim Fang Liu Ping Wang Xiantong Zheng Zhaoying Chen Ding Wang Ali Imran Xin Rong Xuelin Yang Fujun Xu Jing Yang Bo Shen Xinqiang Wang 《半导体学报》2019,40(1):71-75
Monoclinic gallium oxide(Ga_2O_3) has been grown on(0001) sapphire(Al_2O_3) substrate by plasma-assisted molecular beam epitaxy(PA-MBE). The epitaxial relationship has been confirmed to be [010]( 2ˉ01) β-Ga_2O_3||[ 011ˉ0](0001)Al_2O_3 via in-situ reflection high energy electron diffraction(RHEED) monitoring and ex-situ X-ray diffraction(XRD) measurement. Crystalline quality is improved and surface becomes flatter with increasing growth temperature, with a best full width at half maximum(FWHM) of XRD ω-rocking curve of( 2ˉ01) plane and root mean square(RMS) roughness of 0.68° and 2.04 nm for the sample grown at 730 °C,respectively. Room temperature cathodoluminescence measurement shows an emission at ~417 nm, which is most likely originated from recombination of donor–acceptor pair(DAP). 相似文献
4.
Tae-Yeon Seong Jung-Ja Yang Mee Yi Ryu Jong-In Song Phil W. Yu 《Journal of Electronic Materials》1998,27(5):409-413
Chemical beam epitaxial (CBE) GaxIn1?xP layers (x≈0.5) grown on (001) GaAs substrates at temperatures ranging from 490 to 580°C have been investigated using transmission electron diffraction (TED), transmission electron microscopy, and photoluminescence (PL). TED examination revealed the presence of diffuse scattering 1/2{111}B positions, indicating the occurrence of typical CuPt-type ordering in the GaInP CBE layers. As the growth temperature decreased from 580 to 490°C, maxima in the intensity of the diffuse scattering moved from ½{111}B to ½{?1+δ,1?δ,0} positions, where δ is a positive value. As the growth temperature increased from 490 to 550°C, the maxima in the diffuse scattering intensity progressively approached positions of $\frac{1}{2}\{\bar 110\} $ , i.e., the value of δ decreased from 0.25 to 0.17. Bandgap reduction (~45 meV) was observed in the CBE GaInP layers and was attributed to the presence of ordered structures. 相似文献
5.
As part of a systematic investigation of the effects of substrate surfaces on epitaxial growth, the transient behavior of
Hg1−xCdxTe film growth on (111)B CdTe by chemical vapor transport (CVT) has been studied as a function of growth time under vertical
stabilizing (hot end on top) and vertical destabilizing (hot end at bottom) ampoule orientations. The experim ental results
show the morphological transition of the Hg1−xCdxTe deposition on (111)B CdTe at 545°C from three-dimensional islands to layers within about 0.5 and 0.75 h for the growth
under vertical stabilizing and destabilizing conditions, respectively. The combined effects of small convective flow disturbances
on the growth morphology and defect formation are measurable. The overall trends of the time dependent growth rates and compositions
of the Hg1−xCdxTe epitaxial layers under stabilizing and destabilizing conditions are similar. The system atically higher growth rates of
the Hg1−xCdxTe films by about 10% under vertical destabilizing conditions could be influenced by a small convective contribution to the
mass transport. The combined results show that improved Hg1−xCdxTe epitaxial layers of low twin density on (111)B CdTe substrates can be obtained by CVT under vertical stabilizing conditions. 相似文献
6.
P. S. Wijewarnasuriya M. Zandian D. B. Young J. Waldrop D. D. Edwall W. V. Mclevige D. Lee J. Arias A. I. D’Souza 《Journal of Electronic Materials》1999,28(6):649-653
Long wavelength infrared molecular beam epitaxy (MBE) grown p-on-n Hg1−xCdxTe double layer planar heterostructure (DLPH) detectors have been characterized to determine the dominant mechanisms limiting
their performance. Material defects have been identified as critical factors that limit 40K performance operability. This
effort has concentrated on identifying microscopic defects, etch pit density (EPD) and relating these defects to the device
performance. Visual inspection indicates defect densities as high as 105 per cm2 with a spatial extent as observed by atomic force microscope in the range of micrometers extending several micrometers beneath
the surface. At high EPD values (greater than low 106 cm−2) zero bias resistance (R0) at 40K decreases as roughly as the square of the EPD. At 78K, however, measured R0 is not affected by the EPD up to densities as high as mid-106 cm−2. Visual defects greater than 2–3 μm than ∼2 μm in size (micro-void defects) result in either a single etch pit or a cluster
of etch pits. Large variations in a cross-wafer etch pit distribution are most likely a major contributor to the observed
large spreads in 40K R0. This study gives some insight to the present limitation to achieve higher performance and high operability for low temperature
infrared applications on MBE grown HgCdTe material. 相似文献
7.
Ziyan Wang Yan Huang Xiaoshuang Chen Huxian Zhao Wen Lei Wei Lu 《Journal of Electronic Materials》2013,42(11):3054-3058
Arsenic-related defect complexes have been proven responsible for the charge-compensation effects in arsenic-doped Hg1?x Cd x Te, but the underlying mechanism is still unclear. In this study, we systematically investigated the interaction between arsenic donor (AsHg) and mercury vacancy (V Hg) versus the AsHg–V Hg separation in arsenic-doped Hg1?x Cd x Te using first-principles calculations. A new long-range interaction between AsHg and V Hg is found, and the related binding energies and electronic structures are calculated to reveal its coupling mechanism. Our results show that V Hg can increase the distortion of the lattice collaboratively with AsHg due to the different characteristics of AsHg and V Hg in distorting the lattice. The relaxational enhancement as well as the electrical compensation of the AsHg donor is weakened as V Hg moves away from AsHg, and the underlying mechanism is revealed. In addition, a set of defect levels in the band gap generated from the donor–acceptor interaction are also shown, and the origin of these levels is explored. The results of this work are important for theoretically explaining the characteristics of complicated defect levels found in experiments. 相似文献
8.
Laurent Rubaldo Alexandre Brunner Jocelyn Berthoz N. Péré-Laperne A. Kerlain P. Abraham D. Bauza G. Reimbold Olivier Gravrand 《Journal of Electronic Materials》2014,43(8):3065-3069
At high temperature, infra-red focal plane arrays are limited by their performance in operability, detectivity D * or noise equivalent temperature difference. Trap characterization and defect studies are necessary to better understand these limitations at high temperature. In this paper, we use deep level transient spectroscopy to study electrically active defects in mercury cadmium telluride n +/p diodes. The material investigated has a cut-off frequency (λ c) of 2.5 μm at 180 K and p doping performed with mercury vacancy. Trap energy signatures as well as capture cross-section measurements are detailed. A low temperature hole trap close to midgap is observed in the range 150–200 K with an activation energy around 0.18 ± 0.025 eV. A high temperature hole trap is also observed in the range 240–300 K with an activation energy of 0.68 ± 0.06 eV. A hole capture cross-section of 10?19 cm2 is obtained for both traps. The nature of the defects and their correlation with dark current are discussed. 相似文献
9.
S. A. Denisov S. A. Matveev V. Yu. Chalkov V. G. Shengurov Yu. N. Drozdov M. V. Stepikhova D. V. Shengurov Z. F. Krasilnik 《Semiconductors》2014,48(3):402-405
The growth of heterostructures with Si1 ? x Ge x layers on $\left( {1\bar 102} \right)$ sapphire substrates by molecular-beam epitaxy with a silicon sublimation source and a germanium gas source (GeH4) is reported. The systematic study of the influence of substrate temperature and thickness of the silicon buffer layer shows that the optimal conditions for growing epitaxial Si1 ? x Ge x layers are provided at a temperature of T S = 375–400°C. There are significant differences in the orientations of Si1 ? x Ge x layers, depending on the thickness d of the Si buffer layer: the preferred orientations are (100) at d ≥ 100 nm and (110) for thinner layers. Heterostructures with thick (~1 μm) Si1 ? x Ge x layers, doped with erbium atoms, exhibit intense photoluminescence at λ = 1.54 μm. 相似文献
10.
A. Fissel K. Pfennighaus U. Kaiser B. Schröter W. Richter 《Journal of Electronic Materials》1999,28(3):206-213
Epitaxial growth of SiC on hexagonal (or α)-SiC(0001) has been performed by means of solid-source molecular beam epitaxy (MBE). The solid-source MBE growth conditions
have been analyzed concerning the supersaturation and the excess phase formation of silicon and carbon. In general, our results
demonstrate that control of the Si/C ratio and the supersaturation (S) is essential for the growth mode and the kind of polytype
grown. Low temperature (T<1450K) deposition on on-axis SiC substrates always results in the growth of 3C-SiC, which is significantly
improved by an alternating supply of Si and C. On vicinal substrates, a step flow growth mode has been realized at T down
to 1300K. In experiments performed at T>1450K under near surface equilibrium conditions, different growth modes, and conditions
stabilizing the growth of certain polytypes have been found. With a step decrease of S, a step-flow growth mode of both 4H-and
6H-SiC was obtained and, for the first time in case of epitaxial SiC growth, a homogeneous nucleation of α-SiC at more C-rich conditions has been realized. Conditions stabilizing the growth of certain polytypes have been estimated
by thermodynamic calculations considering the influence of polytype structure on the supersaturation and the surface energy.
Based on these results, we have demonstrated the growth of a double-heterostructure by firstly growing a 3C-SiC layer on 4H-SiC(0001)
at low temperature and a subsequent growth of 4H-SiC under near surface equilibrium conditions on a C-stabilized surface on
top of this layer. 相似文献
11.
The main causes of the diffusion spreading of a solid-solution composition near the boundaries of the Si transport channel in a Si/Si1?x Gex heterostructure grown by molecular-beam epitaxy combined with solid (Si) and gaseous (GeH4) sources are considered. For the grown structures, the contributions from various mechanisms involved in forming the profile of the metallurgical boundary of the layer are compared and the effect of channel boundary spreading on the mobility of a two-dimensional electron gas in the channel is evaluated. 相似文献
12.
L. E. A. Berlouis A. W. Wark F. R. Cuickshank D. Pugh P. F. Brevet 《Journal of Electronic Materials》1999,28(6):830-837
Rotation anisotropy by second harmonic generation (SHG) is carried out on epitaxial Hg1−xCdxTe (MCT) and oxide- and sulphide-covered MCT surfaces and shows the fourfold symmetry pattern expected from the {100} surface
(C4v symmetry). The uneven nature of the four peaks confirm the vicinal surface obtained from the growth of the MCT on GaAs {100}
substrate orientated 4° toward the 〈110〉 direction. The increase in the SH intensity observed for the oxide-covered MCT surface
is associated with charge accumulation at the MCT/oxide interface since the oxide is centrosymmetric and cannot generate SH.
The CdS layer on the other hand is strongly nonlinear active and generation here comes from a composite of one noncentrosymmetric
layer on top of another. This leads to interactions in the observed SH arising from the coupling depths (∼40 nm) at the two
interfaces and from the coherence length (∼1200 nm) in the CdS layer. The in-situ SHG measurements during the growth of the anodic oxide and sulphide layers would suggest that a species, most likely HgTe
is embedded in the anodic layer during the initial stages and absorbs the SH radiation at 532 nm. The rotational anisotropy
of the sulphide-covered MCT surface confirms that the CdS layer formed maintains the cubic closed pack symmetry of the underlying
MCT. 相似文献
13.
A. E. Brown M. Jaime-Vasquez L. A. Almeida J. Arias C. M. Lennon R. N. Jacobs J. Pellegrino S. Sivananthan 《Journal of Electronic Materials》2013,42(11):3224-3230
Molecular beam epitaxy n-type long-wavelength infrared (LWIR) Hg1?x Cd x Te (MCT) has been investigated using variable-field Hall measurement in the temperature range from 50 K to 293 K. A quantitative mobility spectrum analysis technique has been used to determine the role of multicarrier transport properties with respect to epilayer growth on lattice-matched cadmium zinc telluride, as well as lattice-mismatched silicon (Si) and gallium arsenide (GaAs) buffered substrates. Overall, after postgrowth annealing, all layers were found to possess three distinct electron species, which were postulated to originate from the bulk, transitional (or higher-x-value) regions, and an interfacial/surface layer carrier. Further, the mobility and concentration with respect to temperature were analyzed for all carriers, showing the expected mobility temperature dependence and intrinsic behavior of the bulk electron. Electrons from transitional regions were seen to match expected values based on the carrier concentration of the resolved peak. At high temperature, the lowest-mobility carrier was consistent with the properties of a surface carrier, while below 125 K it was postulated that interfacial-region electrons may influence peak values. After corrections for x-value and doping density at 77 K, bulk electron mobility in excess of 105 cm2 V?1 s?1 was observed in all epilayers, in line with expected values for lightly doped n-type LWIR material. Results indicate that fundamental conduction properties of electrons in MCT layers are unchanged by choice of substrate. 相似文献
14.
Shubhrangshu Mallick Koushik Banerjee Silviu Velicu Christoph Grein Siddhartha Ghosh Jun Zhao 《Journal of Electronic Materials》2008,37(9):1488-1496
Hg1−x
Cd
x
Te mid-wavelength infrared (MWIR) p
+-n
−-n
+ and p
+-n
− avalanche photodiodes (APDs) with a cut-off of 4.9 μm at 80 K were fabricated on Si substrates. Diode characteristics, avalanche characteristics, and excess noise characteristics
were measured on two devices. Temperature-dependent diode and avalanche characterization was performed. Maximum 3 × 106 Ω cm2 and 9 × 105 Ω cm2 zero-bias resistance times active area (R
0
A) products were measured for the p
+-n
−-n and p
+-n devices at 77 K, respectively. Multiplication gains of 1250 and 410 were measured at −10 and −4 V for the p
+-n
−-n
+ and p
+-n APDs at 77 K, respectively, in the front-illumination mode with the help of a laser with an incident wavelength of 632 nm.
The gains reduce to 200 and 50 at 120 K, respectively. The excess noise factor in all APDs was measured to be in the range
of 1 to 1.2. 相似文献
15.
《Materials Science in Semiconductor Processing》2009,12(3):118-121
Zn1−xCdxO (x= 0.00, 0.05, 0.10, 0.15 and 0.20) thin films were obtained by spray pyrolysis and characterized by XRD, SEM, EDAX and optical measurements. The Zn1−xCdxO microrods are in the wurtzite crystallographic phase with (0 0 2) preferred orientation. A narrowing of the fundamental band gap from 3.30 to 3.10 eV was observed with the increasing nominal Cd content up to 20 at% due to the direct modulation of the band gap caused by Cd substitution. The undoped ZnO film showed two emission bands in the spectra: one sharp UV luminescence at ∼382 nm and one broad visible emission ranging from 430 to 600 nm. The sharp peak at ∼382 nm is split into two at 376 and 400 nm upon Cd doping at levels of 5 and 10 at%. However this splitting is not observed in the doped ZnO samples containing 15 at% Cd and more. It should also be mentioned that the broad peak at the range of 430–600 nm has almost disappeared in the films containing 5, 10 and 15 at% Cd. 相似文献
16.
A. W. Wark L. E. A. Berlouis F. K. Cruickshank D. Pugh P. F. Brevet 《Journal of Electronic Materials》2000,29(6):648-653
In-situ measurements of ellipsometry and second harmonic generation (SHG) were carried out to monitor the electrochemical growth of native anodic oxide films on Hg1?xCdxTe (MCT). Growth of the anodic oxide was performed using two different methods viz., by linear sweep voltammetry and by applying a constant current density. The influence of scan rate and the magnitude of the applied current density on the properties of the growing films were examined. From the ellipsometry data, we have shown that the measured refractive index value of 2.19 for the oxide film remains unchanged for moderate and high oxide growth rates. Only at very slow growth rates were significant increases in the refractive index observed (n=2.4), indicating an increase in the compactness of the layer. For film thicknesses in excess of ~1200 Å, a non-zero value for the extinction coefficient was found, indicating the incorporation of HgTe particles within the anodic oxide film. SHG rotational anisotropy measurements, performed on the MCT with and without an anodic oxide film showed only the four-fold symmetry associated with the MCT and so confirmed that the oxide was centrosymmetric. However, an increase in the SH intensity was observed in the presence of the oxide and this has been attributed to multiple reflections in the thin oxide film and also to the increase in the χ(2) non-linear susceptibility tensor as a result of charge accumulation at the MCT/anodic oxide interface. 相似文献
17.
R. Roucka Y.-J. An A.V.G. Chizmeshya V.R. D’Costa J. Tolle J. Menéndez J. Kouvetakis 《Solid-state electronics》2008,52(11):1687-1690
ZrB2 and HfxZr1?xB2 films were grown on 4° miscut Si(1 1 1) substrates by chemical vapor deposition of gaseous Hf(BH4)4 and Zr(BH4)4. The films display superior structural and optical properties when compared with ZrB2 films grown on on-axis Si(1 1 1). The observed improvements include an optically featureless surface with rms roughness of ~2.5–3.5 nm, a ~50% reduction in the amount of residual strain, and a ~50% lower resistivity. These properties should promote the use of diboride films as buffer layers for nitride semiconductor epitaxy on large-area Si substrates. 相似文献
18.
A. Rodríguez T. Rodríguez A. Kling J. C. Soares M. F. Da Silva C. Ballesteros 《Journal of Electronic Materials》1999,28(2):77-82
The influence of the composition and growth temperature on the strain and defect structure of Si1−xGex layers of 0.21≤x≤0.34 grown on (001) Si wafers by solid phase epitaxy is presented. The strain in the layers was measured
by Raman spectroscopy and Rutherford backscattering spectrometry/channeling angular scans. The defects were analyzed using
high resolution electron microscopy. Three different relaxation mechanisms have been identified and characterized. The first
mechanism occurs at the layer-substrate interface of the samples by the introduction of isolated defects. It is found to be
thermally activated with an activation energy of Ea=0.16 eV and a prefactor that depends on the Gecontent of the layer. This mechanism produces partial relaxation of the layers
and hinders the growth of fully strained layers. The second relaxation mechanism emerges at a distance from the interface
which depends on the stress in the crystallized portion of the layer. In this case, the strain relaxation is caused by stacking
faults that nucleate when they are energetically feasible and propagate toward the surface of the sample during growth. At
low growth temperatures, the defects are confined to the upper part of the epitaxial layers at a distance from the interface
that agrees with the theoretical predictions based on the equilibrium critical layer thickness. The third relaxation mechanism
is introduced at high growth temperature and is based on the gliding of the stacking faults toward the layer-substrate interface.
As a result of this mechanism, the stress in the layers is reduced compared to the stress in the layers grown at lower temperatures
and approaches the equilibrium value corresponding to the total layer thickness. This behavior indicates that the layers grown
at low temperature, where the stacking faults are confined to the upper part, are to some extent metastable. 相似文献
19.
各种组分的(Hg,Cd)Te灵敏高速光电二极管探测器已制成,用于1~3微米的光谱区。这些探测器工作于室温,量子效率为40~70%,比探测度由1.3微米波长的3×10~(11)厘米·赫~(1/2)/瓦到3微米波长的5×10~9厘米·赫~(1/2)/瓦。冷却光电二极管探测器可改进性能。在77°K下2.2微米波长的比探测度测得为2×10~(12)厘米·赫~(1/2)/瓦,接近背景限。对探测器-前置放大器组件进行了响应时间测量,用的是0.9、1.06及1.54微米的脉冲辐射。响应时间约为10毫微秒,似乎与波长无关,但受RC乘积和放大器频带宽的限制。若光电二极管接一频带很宽的放大器,脉冲响应就被RC之积限制到0.5毫微秒,并测得另一时间常数(约为5毫微秒),据说它是由储存的载流子的渡越时间决定的。 相似文献
20.
J. R. Jones S. H. Jones M. F. Zybura L. K. Seidel D. K. Oh 《Journal of Electronic Materials》1991,20(7):709-717
We have selectively grown InxGa1?xAs (0.04 <x < 0.20, 200 ? 7000Å) on rectangular growth areas (100 μm by 200 mil) patterned on GaAs substrates with very low etch pit densities (~200 cm?2). The edge orientations of the growth areas were varied on the substrate resulting in distinct facet formation on the deposited mesa structures. Layers were grown using Low-Pressure Organometallic Chemical Vapor Deposition (LPOMCVD) and all samples were annealed for 1 hr at 700° C. Indium content and film thicknesses were very uniform across a wafer so that only the facet shape was varied. Observation of Crosshatch defect densities as a function of growth window orientation showed that 2900Å In0.08Ga0.92As mesas with [010] edge orientations exhibited no Crosshatch defects. Identical mesas grown in windows with other edge orientations exhibited varying crosshatch defect densities. Large unpatterned areas of growth were heavily crosshatched. This variation in Crosshatch defect density as a function of mesa orientation appears to be associated with non-area related dislocation nucleation mechanisms at the mesa edges. Proper choice of window orientation for patterned substrate epitaxy will allow the mesa facets to be controlled thereby reducing misfit dislocations in the heterostructure interface. 相似文献