Specific features of photoelectric properties of layered films of amorphous hydrogenated silicon

Temperature dependences of photoconductivity of layered and conventional undoped films of amorphous hydrogenated silicon have been studied within a wide range of temperatures (130–420 K) and illumination intensities (0.1–60 mW cm⁻²). It is established that a higher photosensitivity of layered films compared with conventional films is governed by a low dark conductivity of layered films as a consequence of a deeper position of the equilibrium Fermi level in the band gap and the absence of temperature quenching of photoconductivity in these films. It is shown that these specific features of electrical and photoelectric properties of layered films can be attributed to a low concentration of silicon dangling bonds in comparison with the concentration of oxygen-related acceptor centers, which feature a larger capture coefficient for holes.     

Photoluminescence of erbium in amorphous hydrogenated phosphorus-doped silicon

The photoluminescence of erbium ions in phosphorus-doped a-Si:H films has been investigated. The observed increase in the Er photoluminescence with increasing defect density in the samples and the correlation of the temperature variation of the Er photoluminescence and defect-associated photoluminescence intensities are explained on the basis of a model of excitation of Er ions as a result of Auger recombination with defect participation. Fiz. Tekh. Poluprovodn. 31, 869–871 (July 1997)     

Interfacial electrical properties of ion-beam sputter deposited amorphous carbon on silicon

Amorphous, "diamond-like" Carbon films have been deposited on Si substrates, using ion-beam sputtering. The interfacial properties are studied using capacitance and conductance measurements. Data are analyzed using existing theories for interfacial electrical properties. The density of electronic states at the interface, along with corresponding time constants are determined, and the density of interface states is unusually low for an as yet unoptimized.     

Characteristic structural features of amorphous hydrated silicon films deposited by direct-currect decomposition of silane in a magnetic field

Data on the hydrogen content and different forms of hydrogen bonds with silicon in a-Si:H films deposited by direct-current decomposition of silane in a magnetic field (MASD) as a function of the deposition conditions are presented: temperature, pressure of the mixture 25%SiH₄+75%Ar, pumping rate, and insertion of a grid into the discharge chamber. The correlations between the photoconductivity and the structural features of the films are established. Fiz. Tekh. Poluprovodn. 31, 816–819 (July 1997)     

Luminescence of erbium in amorphous hydrogenated silicon obtained by the glow-discharge method

We report the first observation of efficient room-temperature photoluminescence of erbium in amorphous hydrogenated silicon prepared by the plasma chemical-deposition method. Fiz. Tekh. Poluprovodn. 32, 987–989 (August 1998)     

Dependence of photoinduced changes in photovoltaic and dark electrical properties of hydrogenated amorphous silicon diodes on changes in the film properties of hydrogenated amorphous silicon

Computer simulation of hydrogenated amorphous silicon (a-Si:H) p-i-n type or n-i-p type diodes has been used to clarify the relationship between the photoinduced changes in photovoltaic and dark electrical properties of a-Si:H diodes and those in a-Si:H film properties. The origins of observed decrease in the short-circuit current and the fill factor are discussed referring to the decrease in carrier lifetimes, the change in electric field distribution in the undoped layer reflecting the increase in the density of ionized gap states, and the increase in interface recombination velcoity. Possible reasons for the observed differences in the photoinduced changes in photovoltaic properties between p-i-n type and n-i-p type a-Si:H diodes are also discussed. The observed changes in dark current-voltage characteristics of a-Si:H diodes can originate from the decrease in carrier lifetime. Some comments are also made on the "bulk or surface problem" of the photo-induced changes in a-Si:H p-i-n or n-i-p diodes.     

Redistribution of erbium during the crystallization of buried amorphous silicon layers

The redistribution of Er during its implantation in silicon at doses close to the amorphization threshold and its subsequent solid-phase epitaxial (SPE) crystallization is investigated. The formation of a buried amorphous (a) layer is discovered at Er doses equal to 5×10¹³ and 1×10¹⁴ cm⁻² using Rutherford backscattering. The segregation of Er in this case takes place inwardly from the two directions corresponding to the upper and lower boundaries of the buried αlayer and leads to the formation of a concentration peak at the meeting place of the two crystallization fronts. A method for calculating the coordinate dependence of the segregation coefficient k from the distribution profiles of the erbium impurity before and after annealing is proposed. The k(x) curve exhibits a drop, whose width increases with decreasing Er implantation dose. Its appearance is attributed to the nonequilibrium nature of the segregation process at the beginning of SPE crystallization. Fiz. Tekh. Poluprovodn. 33, 652–655 (June 1999)     

RF功率对非晶铟镓锌氧薄膜和器件电学特性的影响

The influence of radio frequency(RF) power on the properties of magnetron sputtered amorphous indium gallium zinc oxide(a-IGZO) thin films and the related thin-film transistor(TFT) devices is investigated comprehensively.A series of a-IGZO thin films prepared with magnetron sputtering at various RF powers are examined.The results prove that the deposition rate sensitively depends on RF power.In addition,the carrier concentration increases from 0.91 x 1019 to 2.15 x 1019 cm-3 with the RF power rising from 40 to 80 W,which may account for the corresponding decrease in the resistivity of the a-IGZO thin films.No evident impacts of RF power are observed on the surface roughness,crystalline nature and stoichiometry of the a-IGZO samples.On the other hand,optical transmittance is apparently influenced by RF power where the extracted optical band-gap value increases from 3.48 to 3.56 eV with RF power varying from 40 to 80 W,as is supposed to result from the carrierinduced band-filling effect.The rise in RF power can also affect the performance of a-IGZO TFTs,in particular by increasing the field-effect mobility clearly,which is assumed to be due to the alteration of the extended states in a-IGZO thin films.     

基于非制冷微测辐射热计的非晶硅锗薄膜电学特性研究

采用等离子体增强化学气相沉积方法(PECVD)制备了应用于微测辐射热计的非晶硅锗薄膜(a-SixGey),并研究了不同反应气体流量比GeH4 /SiH4对薄膜电学性能参数(电阻温度系数TCR和电导率)的影响。研究结果表明,随着流量比GeH4 /SiH4的增大,薄膜电阻温度系数降低,电导率则呈现上升趋势。所制备的薄膜表现出了高TCR值(约3.5%/K-1),适中的电导率(1.47×10-3(Ω·cm)-1)和优良的薄膜电阻均匀性(非均匀性<5%),在微测辐射热计热敏材料领域具有良好的应用前景。Abstract:关键词:Key words:     

The density of states in the mobility gap of amorphous hydrogenated silicon doped with erbium

The effect of doping films of amorphous hydrogenated silicon (a-Si:H) with erbium on the density of the states in the mobility gap is studied. The data obtained are compared with those for a-Si:H films doped with arsenic. The data on the density of the states in the lower and upper halves of the mobility gap are determined from measurements of the spectral dependences of the absorption coefficient and the temperature dependences of the constant and modulated components of the photoconductivity in films exposed to modulated light, respectively. It is shown that doping the a-Si:H films with erbium leads to an increase in the density of states both in the lower and upper halves of the mobility gap.     

Electrical and photoelectric properties of nanostructures obtained by electroless etching of silicon

The electrical and photoelectric properties of nanostructures with porous silicon layers obtained by electroless etching of silicon have been investigated. It is found that the photoelectric and photovoltaic properties of these structures depend on their morphology and are determined by not only the properties of the modified layer, but also the presence of possible barriers in the layered porous silicon. The ratio of the photoconductivity to the dark conductivity reached 10²−5 × 10². An open-circuit voltage V _oc was detected that amounted to ∼250 mV at an incident light power close to AM-1 (∼100 mW/cm²). In this case, the density of short-circuit current I _sc was about 20 μA/cm².     

The influence of the film-substrate interface on the defect densityand other properties of sputter-deposited amorphous hydrogenated silicon

The properties of sputter-deposited amorphous hydrogenated silicon have been found to vary considerably as a function of the film thickness for d<1 μm. This behavior can be interpreted as follows. The defect density decreases exponentially from 2×10¹⁷ cm^-3 at the substrate interface to values below 10¹⁶ cm^-3 in the bulk. A corresponding change in the Urbach energy E₀ indicates that structural inhomogeneities are the reason for the change of the density of states. As a consequence, the ημτ product drops by four orders of magnitude from 1 to 0.01 μm. With electron spin resonance measurements, additional defects that are directly located at the interface are detected. These additional defects might be caused by the creation of a-Si dangling bond-like defects on the surface of the SiO ₂ substrate due to the sputter process     

Effect of the femtosecond laser treatment of hydrogenated amorphous silicon films on their structural, optical, and photoelectric properties

The effect of the femtosecond laser treatment of hydrogenated amorphous silicon (a-Si:H) films on their structural, optical, and photoelectric properties is studied. Under the experimental conditions applied in the study, laser treatment of the film with different radiation intensities induces structural changes that are nonuniform over the film surface. An increase in the radiation intensity yields an increase in the contribution of the nanocrystalline phase to the structure, averaged over the sample surface, as well as an increase in the conductance and photoconductance of the samples. At the same time, for all of the samples, the absorption spectrum obtained by the constant-photocurrent method has a shape typical for those of amorphous silicon. Obtained results indicate the possibility of a-Si:H films photoconductance increase by femtosecond pulse laser treatment.     

Changes in photovoltaic and dark electrical properties of hydrogenated amorphous silicon diodes induced by forward bias carrier injection

The photovoltaic and dark electrical properties of hydrogenated amorphous silicon diodes were changed by forward bias carrier injection for several hours. These changes were similar to photoinduced (PI) changes previously reported, and this result supports previous explanations for PI changes. The differences between these two types of change are also discussed.     

The influence of hydrogen gas on the characteristics of amorphous silicon deposited by RF sputtering

The electrical and optical properties of a-Si depend greatly on the fill gas and substrate temperature during RF sputtering. From the measured absorption coefficient, it was estimated that after the introduction of H₂ gas during sputtering the gap state density reduces from 3.2 × 10¹⁹ cm^?3 to 4.8 × 10¹⁷ cm^?3. As a consequence the optical band gap was found to increase from 1.74 to 1.82 eV. The d.c. conductivity measurement shows three distinct conducting mechanisms at different temperature regions. The SiH bonds in RF sputtered samples are persistant to higher temperature treatment than the CVD prepared ones.     

Production of silicon oxides from glow discharge decomposition of silane and nitric oxide

Films of silicon oxide have been produced by PECVD from NO + SiH4 mixtures. The results indicate that the film properties are less dependent on deposition conditions than when the more usual N2O + SiH4 mixtures are used. The films produced have a high resistivity and good interfacial properties with silicon, but are fairly porous with a relatively high etch rate in p-etch.     

势垒层对黑硅光电探测器性能影响的研究

讨论势垒层Si3N4的引入对黑硅光电探测器光电性能的影响。探测器采用金属一半导体一金属（MSM）器件结构在黑硅层和电极间增加一层势垒层以提高肖特基势垒,从而减低器件的暗电流。实验表明,在相同的光照情况下,有势垒层的探测器暗电流比无势垒层的探测器暗电流至少低1个数量级,且势垒层厚度增加30nm其暗电流降低约1个数量级,而...     

硅表面内铵盐型碳菁膜及光电特性

通过硅氧碳键（ Ｓｉ－ Ｏ－ Ｃ） 将两个内铵盐型碳菁染料在硅表面化学成膜,利用表面增强喇曼光谱（ Ｓ Ｅ Ｒ Ｓ） 和 Ｘ 射线光电子能谱（ Ｘ Ｐ Ｓ） 确证其结构,并测定了键合染料膜硅片的光谱响应和表面光电压。结果表明染料可使硅敏化,且成膜硅片具有光生伏特效应     

Effect of electron irradiation on optical and photoelectric properties of microcrystalline hydrogenated silicon

Semiconductors - The effect of irradiation with 40 keV electrons on the spectral dependence of the absorption coefficient and on the conductivity and photoconductivity of μc-Si:H was studied....     

The electrical properties of anodically grown silicon dioxide films

An electrochemical technique has been used to grow anodic silicon dioxide films of thicknessess between 80 Å and 1100 Å on n-type silicon. The properties of the anodic oxide and the associated Si/SiO₂ interfaces have been studied by forming metal-oxide-semiconductor (MOS) capacitors using the anodically grown oxide as the dielectric. MOS transistors have also been fabricated on n-type silicon using anodic gate oxides 100 Å to 1000 Å thick. Their properties and possible applications are discussed.