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1.
采用热丝化学气相沉积法在p型硅衬底上制备了不同织构的多晶金刚石膜,使用XRD表征了CVD金刚石膜的结构特征, 研究了退火后不同织构金刚石膜的电流特性, 使用Hall效应检测仪研究了金刚石膜的霍尔效应特性及随温度变化的规律, 结果表明所制备的金刚石膜是p型材料, 载流子浓度随着温度的降低而增加, 迁移率随着温度的降低而减小. 室温下[100]织构金刚石薄膜的载流子浓度和迁移率分别为4.3×104 cm-3和76.5 cm2/V·s. 相似文献
2.
Electrical properties of chemically deposited CdS and lithium doped CdS films have been investigated by using techniques of Photo-thermoelectric and Photo-Hall effects. Dark electron densities are independent of temperature between 100 and 330°K because of shallow donors and quasi-intrinsic behaviour is apparent above 330°K. Electron density and mobility in these films have been measured as a function of temperature under strong photoexcitation. The electron mobility is found to be thermally activated with energies 0.2 and 0.22 eV for CdS:Li and CdS films respectively. The Hall mobility and electron density in these films have also been measured as a function of temperature under strong photoexcitation and found that both the free carrier density and mobility are reduced by the adsorption of oxygen, former by larger factor than the latter. The resulting very high electron density and very low electron mobility in the temperature region studied also indicate that most of the photoconductivity in chemically deposited films is caused by an increase in electron density due to photoexcitation. 相似文献
3.
A. R. Tameev R. G. Rakhmeev V. R. Nikitenko R. B. Salikhov A. A. Bunakov A. N. Lachinov A. V. Vannikov 《Physics of the Solid State》2011,53(1):195-200
The electron-hole transport in poly(diphenylene phthalide) films has been investigated. The dependence of the drift mobility
of charge carriers on the excessive mechanical pressure has been studied using the time-of-flight method. It has been revealed
that, with an increase in the thickness of the polymer film, the dispersive transport of charge carries gives way to the quasi-dispersive
transport. In thin films in the prethreshold range (i.e., before switching of the samples to the highly conductive state under
excessive pressure), the electron mobility increases and exceeds the hole mobility. The experimental results have been discussed
in the framework of the model describing the transport through the channels formed by metastable electron-hole pairs. 相似文献
4.
Horst Hoffmann A. Dietrich J. Pickl D. Krause 《Applied Physics A: Materials Science & Processing》1978,16(4):381-390
Indium-tin-oxide films (ITO films) sputtered in Ar-atmosphere with and without addition of oxygen reveal an irreversible increase
in conductivity during annealing in vacuum. This annealing process increases drastically the density of free electrons, while
the Hall mobility changes only slightly. Below the annealing temperature the temperature dependence of the conductivity is
reversible. In films with low density of free electrons, which behave like non-degenerated semiconductors, two activation
energies for the mobility could be found. The irreversible changes, observed during annealing in the vacuum, are explained
by diffusion of oxygen from the interior of the film to the surface, followed by desorption of the oxygen from the surface
into the vacuum. The excess oxygen in the non-stoichiometric films plays the role of electron traps.
The irreversible effects during annealing in the vacuum are partly reversible in the long run. If the annealed films are exposed
to oxygen or air their conductivity decreases because of diffusion of oxygen from the surface into the film. 相似文献
5.
Polycrystalline Cd1?xZnxS films are prepared by the spray pyrolysis technique on amorphous substrate, at different substrate temperatures. The dark conductivity and thermoelectric power are measured and applied to calculate the electron density and mobility. The electron density decreases with increase in substrate temperature. However, mobility is higher for the films prepared at 400°C substrate temperature. The variation of electron density and mobility with substrate temperature is explained in terms of crystallanity of the film and chlorine concentration in the films. The optical absorption of the films are studied and revealed that there is not much change in band gap with substrate temperature. 相似文献
6.
Preliminary investigations show that the avoided level crossing muon spin rotation technique is well suited to the study of
surface-adsorbed free radicals. The samples used were monolayer films of benzene and anisole on small (7 nm and 14 nm) amorphous
silica grains. The observed cyclohexadienyl radical resonances indicate a reduction in mobility down to a temperature of about
125 K, beyond which measurements are unreliable due to weak signals. However, the failure to observe any anisotropy in the
resonances shows that the residual mobility is mainly translational. For a benzene multilayer, on the other hand, we found
clear evidence of anisotropic behaviour, co-existing with signals from a mobile phase. It seems likely that this arises from
a thin fluid surface layer in equilibrium with frozen bulk. 相似文献
7.
利用飞行时间法(time-of-flight)测定了有机小分子发光材料8-羟基喹啉铝(Alq3)与CdSeS量子点掺杂体系的载流子迁移率.研究了Alq3和CdSeS混合薄膜的载流子迁移率与外加电场强度和量子点浓度的变化关系.研究结果表明,CdSeS量子点的掺杂浓度的增加会引起薄膜样品位置无序的增加.除此之外,Alq3和CdSeS量子点界面之间的电荷转移作用,以及在量子点之间进行跳跃传输的电子数量都会改变样品的载流子迁移率.
关键词:
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CdSeS量子点
飞行时间法 相似文献
8.
Manjunatha Pattabi 《Pramana》2002,58(5-6):1141-1145
Aging, which manifests itself as an irreversible increase in electrical resistance in island metal films is of considerable
interest from both academic as well as applications point of view. Aging is attributed to various causes, oxidation of islands
and mobility of islands followed by coalescence (mobility coalescence) being the main contenders. The effect of parameters
like substrate temperature, substrate cleaning, residual gases in the vacuum chamber, ultrasonic vibration of the substrate,
suggest that the mobility coalescence is responsible for the aging in island metal films. Electron microscopy studies show
evidence for mobility of islands at high substrate temperatures. The comparison of aging data of island silver films deposited
on glass substrates in ultra high vacuum and high vacuum suggests that the oxidation of islands, as being responsible for
aging in these films, can be ruled out. Further, under certain conditions of deposition, island silver films exhibit a dramatic
and drastic fall in electrical resistance, marking the insulator-metal transition. This interesting transition observed in
a conservative system — after the stoppage of deposition of the film — is a clear evidence for mobility coalescence of islands
even at room temperature. The sudden fall in resistance is preceded by fluctuations in resistance with time and the fluctuations
are attributed to the making and breaking of the percolation path in the film. 相似文献
9.
Ying Wang Jiangshan Chen Jinying Huang Yanfeng Dai Zhiqiang Zhang Su Liu Dongge Ma 《Applied Physics A: Materials Science & Processing》2014,117(3):1125-1130
Admittance spectroscopy is a powerful tool to determine the carrier mobility. The carrier mobility is a significant parameter to understand the behavior or to optimize the organic light-emitting diode or other organic semiconductor devices. Hole transport in phosphorescent dye, bis[2-(9,9-diethyl-9H-fluoren-2-yl)-1-phenyl-1Hbenzoimidazol-N,C3] iridium(acetylacetonate [(fbi)2Ir(acac)]) doped into N,N-diphenyl-N,N-bis(1-naphthylphenyl)-1,1-biphenyl-4,4-diamine (NPB) films was investigated by admittance spectroscopy. The results show that doped (fbi)2Ir(acac) molecules behave as hole traps in NPB, and lower the hole mobility. For thicker films(?300 nm), the electric field dependence of hole mobility is as expected positive, i.e., the mobility increases exponentially with the electric field. However, for thinner films (?300 nm), the electric field dependence of hole mobility is negative, i.e., the hole mobility decreases exponentially with the electric field. Physical mechanisms behind the negative field dependence of hole mobility are discussed. In addition, three frequency regions were divided to analyze the behaviors of the capacitance in the hole-only device and the physical mechanism was explained by trap theory and the parasitic capacitance effect. 相似文献
10.
Doped SnO2 thin films have been prepared by sputtering from two different targets: antimony doped tin oxide (ATO) and antimony and zinc doped tin oxide (AZTO). In the case of ATO ceramic, the antimony amount only reaches 0.012 mol per formula unit due to its evaporation at high temperature while the presence of Zn2+ in AZTO prevents the antimony evaporation, greatly enhances the ceramic density and allows the deposition of thin films with a high deposition rate. Both types of thin films have a dense morphology with a smooth surface and they are polycrystalline. For post-annealed ATO thin films, the Drude model was applied to deduce the carrier concentration, the optical mobility as well as the resistivity. The carrier concentration is around ten times higher for ATO thin films compared to AZTO. The two combined effects (higher carrier concentration and mobility) for ATO thin films doped with 1.2% of Sb lead to the best optoelectronic performances, confirming previous results obtained with ceramics. Nevertheless, we have a better opportunity to modulate the conductivity in the case of AZTO thin films. 相似文献
11.
The semi-conductive poly(3-iodothiophene)(P3IT) films were fabricated by gas-phase polymerization through a chemical vapor deposition process. The P3IT nanoscale films have a high crystalline morphologies, and possessed a high Hall mobility up to 10 cm2/Vs. The degree of crystalline and the mobility values measured through Scanning Electron Microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy with structural analysis. These conductive thin films, possessing polycrystalline structures, have a very high mobility and are capable of being applied to organic electronic layers for electrical devices such as the thin film transistors and organic photovoltaic cells. 相似文献
12.
Electronic conduction in thermally evaporated thin films of organic semiconductor zinc phthalocyanine (ZnPc) has been investigated in a broad temperature range using gold Ohmic contacts. Electronic conduction by charge carrier hopping was dominated at low temperatures and for all applied voltages. At higher temperatures and at voltages just below 2 V conduction was found to obey Ohm's law, while at higher voltages space-charge-limited conduction (SCLC) was the dominated mechanism, which was controlled by hole-trapping states distributed exponentially within the band gap.In freshly prepared samples adsorbed oxygen was responsible for lower hole mobility and higher charge carrier concentrations. Prolonged heating of ZnPc films at 425 K resulted in lower defect state density, and thus reduced trap concentration and higher charge carrier mobility. 相似文献
13.
采用直流反应磁控溅射方法,通过改变衬底温度并优化生长参数,在玻璃衬底上生长了In-N共掺p型ZnO薄膜。X射线衍射(XRD)测试表明,所得薄膜结晶性能良好,且具有很好的c轴择优取向。Hall测试的结果所得p型ZnO薄膜最低电阻率为35.6Ω·cm,霍尔迁移率为0.111cm2·V-1·s-1,空穴浓度为1.57×1018cm-3。X光电子能谱(XPS)测试表明,铟元素已有效地掺入了ZnO薄膜中,且铟元素有效地促进了氮元素的掺入。紫外可见(UV)透射谱测试表明,在可见光范围内所有薄膜透光率均可达90%。 相似文献
14.
V. V. Randoshkin A. M. Saletskii N. N. Usmanov D. B. Chopornyak 《Physics of the Solid State》2002,44(5):899-901
The mobility of an end domain wall in (Bi,Lu)3(Fe,Ga)5O12 single-crystal garnet ferrite films with (210) orientation is determined by the photoresponse method. It is shown that the mobility of end domain walls in these films is considerably higher than that in (111) single-crystal garnet ferrite films free of rapidly relaxing ions. 相似文献
15.
为了解退火对硅基锗薄膜的质量、红外吸收、透射率和电学性质的影响,采用分子束外延方法用两步法在硅基上生长锗薄膜。将生长后的样品分成两部分,其中一部分进行了退火处理。对退火前后的样品用高分辨X射线双晶衍射仪测量了(400)晶面的X射线双晶衍射摇摆曲线,用傅里叶红外光谱仪测量了红外透射率和吸收谱,并用霍尔效应仪测量了退火前后样品的载流子浓度、迁移率、电阻率、电导率和霍尔系数。结果表明,退火后的薄膜质量明显提高。退火后大部分区域吸收增大,透射率明显减小,615~3 730 cm-1区间的透射率均比退火前降低了20%以上。退火后的体载流子浓度增大到退火前的23.26倍,迁移率增大到退火前的27.82倍。 相似文献
16.
《Current Applied Physics》2014,14(5):691-696
The thermal degradation characteristics of Al doped ZnO (AZO) films, which were prepared by radio frequency magnetron sputtering at room temperature and subsequently annealed in air, were examined by making comparisons with those of the as-deposited and the vacuum-annealed AZO films. AZO films annealed in air at temperature higher than 300 °C exhibited severely degraded conductivity due to the decrease of carrier concentration and Hall mobility, which could be interpreted as grain boundary scattering from the thermally activated mobility behavior. Experimental observations, that vacuum-annealing of the as-deposited AZO film led to substantial reduction in carrier concentration and that subsequent vacuum-annealing of the air-annealed AZO film could not restore the carrier concentration unlike the restoration of Hall mobility up to 80%, led to a perception that substantial amount of free carriers in the as-deposited AZO film were generated from oxygen vacancies. It was proposed that ratios of the barrier height to the Fermi level, which were determined by taking into account the non-parabolic nature of the conduction band, could be used as a measure for the influence of grain boundary scattering on the overall electron transport mechanism in AZO films. 相似文献
17.
Effect of substrates on the properties of p-type ZnO films 总被引:2,自引:0,他引:2
X.D. Zhang H.B. Fan J. Sun Y. Zhao 《Physica E: Low-dimensional Systems and Nanostructures》2007,39(2):267-270
Influence of substrates on the properties of p-type ZnO films, which were fabricated by N–Al co-doping technique, was studied. Hall measurement results indicated that ZnO films deposited on common glass substrate were p-type conductivity when Zn:N:Al atomic ratio amounts to 1:3:0.1. However, ZnO films deposited on corning 7059 glass substrate showed n-type conductivity. Secondary ion mass spectroscopy demonstrated that Na content incorporated into ZnO films deposited on common glass substrate was more evident than that of corning 7059 glass. In addition, Hall mobility and conductivity of p-type ZnO thin films deposited on silicon substrate were improved largely. 相似文献
18.
《Current Applied Physics》2015,15(8):897-901
Tin(II) sulfide (SnS) films are one of the most promising absorber materials for high efficiency solar cells without using rare metals. In this work, SnS films were deposited by the thermal evaporation on glass substrates under the variation of growth temperatures of 100–250 °C. It was revealed that the SnS thin film prepared under the temperature of 100 °C had relatively small crystal grains. On the other hand, the denser and larger crystal grains of the SnS films were obtained with the constant compositions, when the growth temperature increased to 225 °C. With the temperature of higher than 225 °C, the SnS began to be re-evaporated from the films. The highest Hall mobility of the films was obtained under the temperature of 200 °C. Ultimately, the results suggested that the optimized growth temperature of SnS by the evaporation is 200 °C, giving rise to compact and large crystal grains and the highest Hall mobility, thereby contributing to the 2.53%-efficient SnS thin-film solar cell. 相似文献
19.
H/Al共掺杂对ZnO基透明导电薄膜光电性质和晶体结构的影响 总被引:1,自引:0,他引:1
利用H在ZnO中作为浅施主杂质的特性,研究了H掺杂对ZnO:Al透明导电薄膜特性的影响。通过降低ZnO:Al中Al的含量并同时引入H掺杂,解决了透明导电薄膜中高导电性与高透过率之间的矛盾。H的掺杂可以显著降低ZnO基透明导电薄膜的电阻率,这是由于H一方面作为施主可以提供电子从而提高了自由载流子浓度;另一方面与ZnO晶界中的O-结合降低了晶界势垒,提高了载流子迁移率。利用H掺杂,可以在Al掺杂量降低10倍的情况下,仍然能获得低电阻率(6.3×10-4 Ω·cm)的透明导电薄膜,同时其近红外波段(1 200 nm)透光率从64%提高到90%。这种具有高导电性和高透光性的透明导电薄膜可以应用于各类薄膜太阳能电池中以提升器件效率。 相似文献