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1.
Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) transmission, and Hall effect measurements were performed to investigate the structural, optical, and electrical properties of as-grown and in situ-annealed Hg0.7Cd0.3Te epilayers grown on CdTe buffer layers by using molecular beam epitaxy. After the Hg0.7Cd0.3Te epilayers had been annealed in a Hg-cell flux atmosphere, the SEM images showed that the surface morphologies of the Hg0.7Cd0.3Te thin films were mirror-like with no indication of pinholes or defects, and the FTIR spectra showed that the transmission intensities had increased in comparison to that of the as-grown Hg0.7Cd0.3Te epilayer. Hall-effect measurements showed that n-Hg0.7Cd0.3Te epilayers were converted to p-Hg0.7Cd0.3Te epilayers. These results indicate that the surface, optical, and electrical properties of the Hg1 − xCdxTe epilayers are improved by annealing and that as-grown n-Hg1 − xCdxTe epilayers can be converted to p-Hg1 − xCdxTe epilayers by in situ annealing. 相似文献
2.
《Infrared physics》1993,34(1):37-41
Reverse bias dark currents in p-n junctions fabricated in undoped CdxHg1−xTe (CMT) (0.22 < x < 0.24) LPE epilayers by ion implantation of boron have been studied at different temperatures. The behaviour of current-voltage (I–V) characteristics at temperatures below 80 K allows us to discriminate two types of material. The first group consists of samples with currents dominated by a band-to-band tunnelling mechanism. The second is characterized by the current which exceeds that in the first group. The excess currents proved to be connected with fluctuations of charged impurity density which changed local tunnel transparency of the potential barriers. This mechanism is likely to dominate current in closely compensated samples. A quantitative analysis of I–V characteristics is made. 相似文献
3.
H. Duan Y.Z. Dong Z.P. Lin Y. Huang X.S. Chen W. Lu 《Solid State Communications》2012,152(18):1725-1728
The as-grown arsenic-doped HgCdTe typically exhibits compensated n-type conductivity. Based on first-principles calculations, we identify Hg vacancies (VHg) as a dominant defect species involved in the compensation. Arsenic donor (AsHg) and VHg acceptor no doubt tend to combine into complex defects but little has been recognized about the features of the complex defects in precious studies. These features outlined in this work enable us to provide a consistent explanation for arsenic activation mechanism proposed by Zandian et al. [7] and Berding et al. [8]. 相似文献
4.
P.?Madejczyk A.?Piotrowski K.?K?os W.?Gawron J.?Rutkowski A.?Rogalski 《Opto-Electronics Review》2010,18(3):271-276
The acceptor doping of mercury cadmium telluride (HgCdTe) layers grown by MOCVD are investigated. (111)HgCdTe layers were
grown on (100)GaAs substrates at 350°C using horizontal reactor and interdiffused multilayer process (IMP). TDMAAs and AsH3
were alternatively used as effective p-type doping precursors. Incorporation and activation rates of arsenic have been studied.
Over a wide range of Hg1−xCdxTe compositions (0.17 < x < 0.4), arsenic doping concentration in the range from 5×1015 cm−3 to 5×1017 cm−3 was obtained without postgrowth annealing. The electrical and chemical properties of epitaxial layers are specified by measurements
of SIMS profiles, Hall effect and minority carrier lifetimes. It is confirmed that the Auger-7 mechanism has decisive influence
on carrier lifetime in p-type HgCdTe epilayers. 相似文献
5.
Xia Liu Hang Song Guoqing MiaoHong Jiang Lianzhen Cao Dabing LiXiaojuan Sun Yiren Chen 《Applied Surface Science》2011,257(6):1996-1999
In0.82Ga0.18As epilayers were grown on InP substrates using a two-step growth technique by LP-MOCVD. A homogeneous low-temperature (450 °C) In0.82Ga0.18As buffer layer was introduced to improve the crystalline quality of epilayers. The influence of low-temperature buffer layer deposition condition, such as thermal annealing duration, on the crystalline quality of the In0.82Ga0.18As epilayer was investigated. Double-crystal X-ray diffraction measurement, Hall measurement, and Raman scattering spectrum were used to evaluate the In0.82Ga0.18As epilayers. Atomic force microscope was used to study the surface morphology. It is found that the In0.82Ga0.18As epilayer, with buffer layer thermal annealing for 5 min, exhibits the best crystalline quality. The change of the surface morphology of the buffer layer after thermal annealing treatment was suggested to explain the phenomenon. 相似文献
6.
High-temperature laser annealing for thin film polycrystalline silicon solar cell on glass substrate
A. Chowdhury J. Schneider J. Dore F. Mermet A. Slaoui 《Applied Physics A: Materials Science & Processing》2012,107(3):653-659
Thin film polycrystalline silicon films grown on glass substrate were irradiated with an infrared continuous wave laser for defects annealing and/or dopants activation. The samples were uniformly scanned using an attachment with the laser system. Substrate temperature, scan speed and laser power were varied to find suitable laser annealing conditions. The Raman spectroscopy and Suns-V oc analysis were carried out to qualify the films quality after laser annealing. A maximum enhancement of the open circuit voltage V oc of about 100?mV is obtained after laser annealing of as-grown polysilicon structures. A strong correlation was found between the full width half maximum of the Si crystalline peak and V oc. It is interpreted as due to defects annealing as well as to dopants activation in the absorbing silicon layer. The maximum V oc reached is 485?mV after laser treatment and plasma hydrogenation, thanks to defects passivation. 相似文献
7.
P.N.K. Deenapanray H.H. Tan C. Jagadish 《Applied Physics A: Materials Science & Processing》2003,76(6):961-964
Defects created in rapid thermally annealed n-GaAs epilayers capped with native oxide layers have been investigated using
deep-level transient spectroscopy (DLTS). The native oxide layers were formed at room temperature using pulsed anodic oxidation.
A hole trap H0, due to either interface states or injection of interstitials, is observed around the detection limit of DLTS
in oxidized samples. Rapid thermal annealing introduces three additional minority-carrier traps H1 (EV+0.44 eV), H2 (EV+0.73 eV), and H3 (EV+0.76 eV). These hole traps are introduced in conjunction with electron traps S1 (EC-0.23 eV) and S2 (EC-0.45 eV), which are observed in the same epilayers following disordering using SiO2 capping layers. We also provide evidence that a hole trap whose DLTS peak overlaps with that of EL2 is present in the disordered
n-GaAs layers. The mechanisms through which these hole traps are created are discussed. Capacitance–voltage measurements reveal
that impurity-free disordering using native oxides of GaAs produced higher free-carrier compensation compared to SiO2 capping layers.
Received: 12 March 2002 / Accepted: 15 July 2002 / Published online: 22 November 2002
RID="*"
ID="*"Corresponding author. Fax: +61-2/6125-0381, E-mail: pnk109@rsphysse.anu.edu.au 相似文献
8.
《Current Applied Physics》2018,18(6):626-632
The selective catalytic reduction (SCR) system for NOX removal in coal-fired power plants has a promoting effect on the oxidation and removal of elemental mercury. In this study, basic mechanism of mercury oxidation by V2O5-based SCR catalyst is investigated via density functional theory method and the periodic slab models. Calculations are conducted to determine the adsorption energies and geometries of Hg0, HgCl, HgCl2 and HCl on V2O5(001) surface, and to reveal the energy profile of oxidation reaction and the structures of relative transition states and intermediates. The results indicate that HCl can significantly promote Hg0 oxidation on V2O5(001) surface, by forming an intermediate HgCl-surface which is important for Hg0 oxidation. The Hg0 oxidation goes through Hg0 → HgCl → HgCl2, and the two stages of the reaction follow Eley–Rideal mechanism and Langmuir-Hinshelwood mechanism, respectively. The formation of HgCl2 is the rate-determining step due to its high energy barrier. Three detailed reaction pathways are obtained, and the related energy profiles and structures are analyzed in detail. The Hg0 oxidation reaction can take place through all three pathways even if differences exist in each other, while pathways I and II have relatively low energy barriers. 相似文献
9.
利用水平式低压热壁CVD (LP-HW-CVD) 生长系统,台阶控制生长和衬底旋转等优化技术,在偏晶向的4H-SiC Si(0001) 晶面衬底上进行4H-SiC同质外延生长,生长温度和压力分别为1550℃和104 Pa,用高纯N2作为n型掺杂剂的4H-SiC原位掺杂技术,生长速率控制在5μm/h左右.采用扫描电镜(SEM)、原子力显微镜(AFM),傅里叶变换红外光谱(FTIR)和Hg/4H-SiC肖特基结构对同质外延表面形貌、厚度、掺杂浓度以及均匀性进行了测试.实验结果表明,4H-SiC同质外延在表面无明显缺陷,厚度均匀性1.74%, 1.99% 和1.32%(σ/mean),掺杂浓度均匀性为3.37%,2.39%和2.01%.同种工艺条件下,样品间的厚度和掺杂浓度误差为1.54%和3.63%,有很好的工艺可靠性.
关键词:
4H-SiC
同质外延生长
水平热壁CVD
均匀性 相似文献
10.
Peter Bury Hikaru Kobayashi Masao Takahashi Kentaro Imamura Peter Sidor Franti??ek ??ernobila 《Central European Journal of Physics》2009,7(2):237-241
Ultrathin silicon dioxide (SiO2) layers formed on Si substrate with nitric acid have been investigated using both acoustic deep-level transient spectroscopy
(A-DLTS) and electrical methods to characterize the interface states. The set of SiO2/Si structures formed in different conditions (reaction time, concentrations of nitric acid (HNO3), and SiO2 thickness [3–9 nm]) was prepared. The leakage current density was decreased by post-oxidation annealing (POA) treatment at
250°C in pure nitrogen for 1 h and/or post-metallization annealing (PMA) treatment at 250°C in a hydrogen atmosphere for 1
h. All structures of the set, except electrical investigation, current-voltage (I - V), and capacitance — voltage (C - V) measurements, were investigated using A-DLTS to find both the interface states distribution and the role of POA and/or PMA
treatment on the interface-state occurrence and distribution. The evident decreases of interface states and shift of their
activation energies in the structures with PMA treatment in comparison with POA treatment were observed in most of the investigated
structures. The results are analyzed and discussed.
相似文献
11.
Yingju Yang Jing Liu Zhen Wang Yingni Yu 《Proceedings of the Combustion Institute》2021,38(3):4317-4325
Experiments and density functional theory calculations were conducted to uncover the reaction chemistry of Hg0 oxidation during SO2/SO3 conversion over V2O5/TiO2 catalyst. The results show that SO2 promotes Hg0 oxidation over V2O5/TiO2 catalyst with the assistance of oxygen. The promotional effect is dependent on the reaction temperature, and is associated with the bimolecular reaction between Hg0 and SO3 over V2O5/TiO2 catalyst. SO2 can be oxidized to SO3 which has high oxidation ability for Hg0 oxidation. SO2/SO3 conversion proceeds through a three-step reaction process in the sequence of SO2 adsorption → SO2 oxidation → SO3 desorption. SO2 oxidation presents an activation energy barrier of 223.84 kJ/mol. HgSO4 species is formed from the bimolecular reaction between Hg0 and SO3 over V2O5/TiO2 catalyst. Hg0 oxidation by SO3 over V2O5/TiO2 catalyst occurs through three reaction pathways, which are energetically favorable for HgSO4 formation. SO2* → SO3* is identified as the rate-determining step of HgSO4 formation. During Hg0 oxidation by SO3 over V2O5/TiO2 catalyst, HgSO4 desorption is a highly endothermic reaction process and requires a higher external energy. The proposed skeletal reaction network can be used to well understand the reaction mechanism of Hg0 oxidation during SO2/SO3 conversion over V2O5/TiO2 catalyst. 相似文献
12.
Way Foong Lim Zainovia Lockman Kuan Yew Cheong 《Applied Physics A: Materials Science & Processing》2012,107(2):459-467
Metal-organic decomposed lanthanum cerium oxide (La
x
Ce
y
O
z
) film had been spin-coated on n-type Si substrate. Effects of post-deposition annealing temperature and time on the metal-oxide-semiconductor
(MOS) properties of the film were studied. As temperature increased from 400 to 1000°C for 15 minutes dwell time, La
x
Ce
y
O
z
demonstrated a decrease in interface trap density (D
it) and total interface trap density (D
total), which were related to the formation of SiO
x
/silicates interfacial layer (IL). The lowest leakage current density and highest dielectric breakdown voltage (V
B) was obtained in 1000°C-annealed sample. When longer annealing times (30–120 minutes) were studied on the 1000°C-annealed
sample, the sample annealed at 1000°C for 120 min showed the best MOS characteristics with V
B of 30 V. Reasons contributing to such observation were discussed. 相似文献
13.
14.
H. Nakagawa 《Applied Surface Science》2008,254(20):6648-6652
To compare the annealing effects on GaMnAs-doped with Zn (GaMnAs:Zn) and undoped GaMnAs (u-GaMnAs) epilayers, we grew GaMnAs thin films at 200 °C by molecular beam epitaxy (MBE) on GaAs substrates, and they were annealed at temperatures ranging from 220 °C to 380 °C for 100 min in air. These epilayers were characterized by high-resolution X-ray diffraction (XRD), electrical, and magnetic measurements. A maximum resistivity at temperatures Tm close to the Curie temperatures Tc was observed from the measurement of the temperature-dependent resistivity ρ(T) for both the GaMnAs:Zn and the u-GaMnAs samples. We found, however, that the maximum temperature Tm observed for GaMnAs:Zn epilayers increased with increasing annealing temperature, which was different from the result with the u-GaMnAs epilayers. The formation of GaAs:Zn and MnAs or Mn-Zn-As complexes with increasing annealing temperature is most likely responsible for the differences in appearance. 相似文献
15.
We have measured the equation of state of the intermetallic compound AuIn2 up to 20 GPa and Cd0.8Hg0.2 up to 50 GPa using methanol-ethanol-water solution or argon as pressure media. In the experiments performed with argon as pressure medium, we minimized non-hydrostatic conditions by thermally annealing the sample. We present data revealing compressibility anomalies in AuIn2 at 2.7 GPa and in Cd0.8Hg0.2 near 8, 18 and 34 GPa with methanol-ethanol-water and argon. At pressures above 5 GPa the P-V data for AuIn2 and Cd0.8Hg0.2 from experiments preformed with argon as a pressure medium start deviating from those using methanol-ethanol-water, and the equation of state based on experiments in argon is stiffer compared with that in methanol-ethanol-water. This behavior is consistent with the relative merits of the two pressure transmitting media as documented in the literature. We also provide a brief summary of the results of electronic structure calculations that associate these anomalies with electronic topological transitions. 相似文献
16.
Yoon Shon S.-W. Lee Sejoon Lee H.C. Jeon T.W. Kang Chong S. Yoon Jeoung Ju Lee 《Applied Surface Science》2007,254(2):494-498
InMnP:Zn epilayers doped with Mn (0.290 at.%) were annealed at 723-873 K for 60 s and 473-573 K for 30 min. Using Auger electron spectroscopy, the changes in concentration profiles of the epilayers correlated to the ferromagnetic origin as a function of the annealing conditions. The epilayers annealed at 723-873 K for 60 s exhibited InMn3 persisting up to 583 K. For InMnP:Zn epilayers annealed at 523-573 K for 30 min, the concentration depth profiles remained flat so that the stoichiometry was well maintained without precipitates such as InMn3 and MnP comparable to the as-grown InP:Zn before doping Mn. These samples showed clear ferromagnetic hysteresis loops. Curie temperature was about 150 K. A ferromagnetic hysteresis loop was obtained even at very lower annealing temperature of 473 K. 相似文献
17.
《Journal of Physics and Chemistry of Solids》1986,47(1):105-108
Se-doped GaAs epilayers grown by low-pressure MOCVD were studied. Triethylgallium and arsine were used as Ga and As sources, respectively. Layers of high crystalline quality can be obtained. The carrier concentrations of epilayers were greatly influenced by the flow rates of TEG, AsH3 and H2Se as well as the growth temperatures. The carrier concentration versus these parameters can be explained well by a simplified model. Carrier concentration versus TEG mole fraction may be expressed as n ∝ (TEG)+0.5. The I-V characteristics of the Schottky diode were also investigated. The ideality factor is about 1.53. 相似文献
18.
高组份Al值的AlxGa1-x As和AlxGa1-x As/GaAs/AlxGa1-xAs/GaAs多层结构的MOCVD生长 总被引:1,自引:1,他引:0
用自制常压MOCVD系统,在半绝缘GaAs衬底上生长高Al组份AlxGa1-xAs(其x值达0.83),和AlxGa1-xAs/GaAs/AlxGa1-xAs/GaAs多层结构,表面镜面光亮。生长层厚度从几十到十几μm可控,测试表明外延层晶格结构完整,x值调节范围宽,非有意掺杂低,高纯GaAs外延层载流子浓度n300K=1.7×1015cm-3,n77K=1.4×1015cm-3,迁移率μ300K=5900cmcm2/V.S,μ77K=55500cm2/V.S。用电子探针,俄歇能谱仪测不出非有意掺杂的杂质,各层间界面清晰平直。 对GaAs,AlGaAs生长层表面缺陷,衬底偏角生长温度及其它生长条件也进行了初步探讨。 相似文献
19.
This study demonstrates quantum-dot light-emitting diodes (QD-LEDs) with a function of resistive switching memory, capable of on/off operation at the same driving current depending on reset/set state. The QD-LEDs were fabricated by spin-coating process and experienced two different annealing conditions, which yielded defective or less-defective V2O5–x layer. One of the annealing conditions produced QD-LEDs with the unusual electrical behaviors of negative differential resistance (NDR), capacitance oscillation, and voltage–current hysteresis curves, signifying so-called resistive switching characteristics. X-ray and ultraviolet photoelectron spectroscopies were used to examine the chemical state of the differently annealed V2O5–x layers. The less stoichiometric V2O5–x layer was found to be responsible for the resistive switching behaviors of the NDR and the low and high resistance states (LRS and HRS, respectively). We discuss the LRS/HRS of V2O5–x for resistive switching in terms of a conductive filament effect, induced by microstructural changes caused by oxygen drift and vacancy annihilation processes in the high defect density V2O5–x layer. 相似文献
20.
Studies of luminescence properties of ZnO and ZnO:Zn nanorods prepared by solution growth technique 总被引:1,自引:0,他引:1
M.K. Patra 《Journal of luminescence》2008,128(2):267-272
Pyramidal ZnO nanorods with hexagonal structure having c-axis preferred orientation are grown over large area silica substrates by a simple aqueous solution growth technique. The as-grown nanorods were studied using XRD, SEM and UV-vis photoluminescence (PL) spectroscopy for their structural, morphological and optical properties, respectively. Further, the samples have also been annealed under different atmospheric conditions (air, O2, N2 and Zn) to study the defect formation in nanorods. The PL spectra of the as-grown nanorods show narrow-band excitonic emission at 3.03 eV and a broad-band deep-level emission (DLE) related to the defect centers at 2.24 eV. After some mild air annealing at 200 °C, fine structures with peaks having energy separation of ∼100 meV were observed in the DLE band and the same have been attributed to the longitudinal optical (LO) phonon-assisted transitions. However, the annealing of the samples under mild reducing atmospheres of N2 or zinc at 550 °C resulted in significant modifications in the DLE band wherein high intensity green emission with two closely spaced peaks with maxima at 2.5 and 2.7 eV were observed which have been attributed to the VO and Zni defect centers, respectively. The V-I characteristic of the ZnO:Zn nanorods shows enhancement in n-type conductivity compared to other samples. The studies thus suggest that the green emitting ZnO:Zn nanorods can be used as low voltage field emission display (FED) phosphors with nanometer scale resolution. 相似文献