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1.
Inverse staggered polycrystalline silicon (poly-Si) and hydrogenated amorphous silicon (a-Si:H) double structure thin-film transistors (TFT's) are fabricated based on the conventional a-Si:H TFT process on a single glass substrate. After depositing a thin (20 nm) a-Si:H using the plasma CVD technique at 300°C, Ar+ and XeCl (300 mJ/cm2) lasers are irradiated successively, and then a thick a-Si:H (200 nm) and n+ Si layers are deposited again. The field effect mobilities of 10 and 0.5 cm 2/V·s are obtained for the laser annealed poly-Si and the a-Si:H (without annealing) TFT's, respectively  相似文献   

2.
Mo-gate n-channel poly-Si thin-film transistors (TFT's) have been fabricated for the first time at a low processing temperature of 260°C. A 500-1000-A-thick a-Si:H was successfully crystallized by XeCl excimer laser (308nm) annealing without heating a glass substrate. TFT's were fabricated in the crystallized Si film. The channel mobility of the TFT was 180cm2/V.s when the a-Si:H was crystallized by annealing with a laser having an energy density of 200 mJ/cm2. This result shows that high-speed silicon devices can be fabricated at a low temperature using XeCl excimer laser annealing.  相似文献   

3.
A method to control the size of nanoscale silicon grown in thermally annealed hydrogenated amorphous silicon (a-Si : H) films is reported. Using the characterizing techniques of micro-Raman scattering,X-ray diffraction and computer simulation, it is found that the sizes of the formed silicon particles change with the temperature rising rate in thermally annealing the a-Si : H films. When the a-Si: H films have been annealed with high rising rate( ~ 100 C/s), the sizes of nanoscale silicon particles are in the range of 1.6~ 15nm. On the other hand, if the a-Si: H films have been annealed with low temperature rising rate(~1 C/s),the sizes of nanoscale silicon particles are in the range of 23~46 nm. Based on the theory of crystal nucleation and growth, the effect of temperature rising rate on the sizes of the formed silicon particles is discussed. Under high power laser irradiation, in situ nanocrystallization and subsequent nc-Si clusters are small enough for visible light emission, authors have not detected any visible photoluminescence(PL) from these nc-Si clusters before surface passivation. After electrochemical oxidization in hydrofluoric acid, however, intense red PL has been detected. Cyclic hydrofluoric oxidization and air exposure can cause subsequent blue shift in the red emission. The importance of surface passivation and quantum confinement in the visible emissions has been discussed.  相似文献   

4.
A method to control the si ze of nanoscale silicon grown in thermally annealed hydrogenated amorphous silico n (a-Si∶H) films is reported. Using the characterizing techniques of micro-Ra man scattering, X-ray diffraction and computer simulation, it is found that the sizes of the formed silicon particles change with the temperature rising rate i n thermally annealing the a-Si∶H films. When the a-Si∶H films have been anne aled with high rising rate( ~100 ℃/s), the sizes of nanoscale silicon particle s are in the range of 1.6~15 nm. On the other hand, if the a-Si∶H films have been annealed with low temperature rising rate(~1 ℃/s), the sizes of nanoscale silicon particles are in the range of 23~46 nm. Based on the theory of crystal nucleation and growth, the effect of temperature rising rate on the sizes of th e formed silicon particles is discussed. Under high power laser irradiation, in situ nanocrystallization and subsequent nc-Si clusters are small enough for vis ible light emission, authors have not detected any visible photoluminescence(PL) from these nc-Si clusters before surface passivation. After electrochemical ox idization in hydrofluoric acid, however, intense red PL has been detected. Cycli c hydrofluoric oxidization and air exposure can cause subsequent blue shift in t he red emission. The importance of surface passivation and quantum confinement i n the visible emissions has been discussed.  相似文献   

5.
A thin-film transistor (TFT) with a maximum field-effect mobility of 320 cm2/V-s, an on/off current ratio of 7.6×107 , a threshold voltage of 6.7 V and a subthreshold slope of 0.37 V/decade was fabricated by using pulse laser annealing processes. Amorphous silicon films (a-Si:H) with a very low impurity concentration of 4×1018 cm-3 for oxygen, 1.5×1018 cm-3 for carbon, and 2×1017 cm-3 for nitrogen were deposited by a plasma chemical vapor deposition (CVD) method and annealed by KrF excimer laser (wavelength of 248 nm). The Raman spectroscopy technique was a useful tool for optimizing laser annealing conditions. Experimental results show that two factors are very important for fabricating very-high mobility TFTs: (1) utilizing high-purity as-deposited a-Si:H film; and (2) performing whole laser annealing processes sequentially in a vacuum container and optimizing illumination conditions  相似文献   

6.
报道了控制热处理过程中含氢非晶硅中纳米硅颗粒大小的一种新方法。用喇曼散射、X射线衍射和计算机模拟,发现在非晶硅中所形成的纳米硅颗粒的大小,随着热退火过程中升温速率的变化而变化。在退火过程中,若非晶硅薄膜升温速率较高(~100℃/s),则所形成纳米硅粒的大小在1.6~15nm;若非晶硅薄膜升温速率较低(~1℃/s),则纳米硅粒大小在23~46nm。根据晶体生长理论,讨论了升温速率的高低与所形成的纳米硅颗粒大小的关系。  相似文献   

7.
薛清  李冠成  王秉坤 《半导体技术》2004,29(10):20-21,26
报道了利用快速退火法控制膜中纳米硅粒大小的方法,讨论了升温快慢与所形成的纳米硅粒大小的关系.  相似文献   

8.
含氢非晶硅薄膜经过快速热退火处理后,我们用拉曼散射和X-射线衍射技术对样品进行分析.我们的实验结果表明:在非晶硅薄膜中形成的纳米硅晶粒的大小随着热退火过程中升温快慢而变化.在升温过程中,当单位时间内温度变化量较大时(~100℃/s),则所形成纳米硅粒较小(~1.6~15nm);若单位时间内温度变化量较低(~1℃/s),则纳米硅粒较大(~23~46nm)。根据分形生长理论和计算机模拟,我们讨论了升温快慢与所形成的纳米硅颗粒大小的关系.  相似文献   

9.
快速光热退火法制备多晶硅薄膜的研究   总被引:5,自引:1,他引:4  
为了制备应用于太阳电池的优质多晶硅薄膜,研究了非晶硅薄膜的快速光热退火技术。先利用 PECVD 设备沉积非晶硅薄膜,然后放入快速光热退火炉中进行退火。退火前后的薄膜利用 X 射线衍射仪(XRD)和扫描电子显微镜(SEM)测试其晶体结构及表面形貌,用电导率设备测试其暗电导率。研究表明退火温度、退火时间对非晶硅薄膜的晶化都有很大的影响,光热退火前先用常规高温炉预热有助于增大多晶硅薄膜的晶粒尺寸和暗电导率。  相似文献   

10.
The characteristics of amorphous silicon hydrogen and deuterium thin-film transistors (a-Si:H/a-Si:D TFT) were studied. The deuterated and hydrogenated amorphous silicon channels were prepared by first annealing the as-deposited a-Si:H layer at 550°C in N2 environment to expel all the hydrogen atoms out of the films, then the D 2 or H2 plasma were applied to treat the amorphous silicon layers. The field effect mobility of the conventional hydrogen TFT is usually smaller than 1 cm2/V-s. It was found that substitution of hydrogen with deuterium improved the field effect mobility of the TFT. The maximum field effect mobility of a-Si:D TFT obtained from the saturation region was 1.77 cm2/V-s  相似文献   

11.
Low resistivity layers have been formed at low process temperatures, by high dose Co+ ion implantation in to hydrogenated amorphous silicon (a-Si:H) and amorphous silicon carbide (a-SiC:H). The lowest resistivities, of the order of 10 ohms/Sq, have been observed for the carbon-free films (a-Si:H) and can be obtained at annealing temperatures of <250°C. Schottky barrier contacts to the a-Si:H films exhibit near ideal behavior with low leakage currents, of the order 10−9 A·cm−2. The electrical properties of the amorphous films are assessed as a function of ion dose, dose rate and annealing conditions, with a view to optimizing these parameters.  相似文献   

12.
报道了氢化非晶硅薄膜在600~620℃温度下快速退火10 s可以形成纳米晶硅,其拉曼散射表明,所形成的纳米晶硅在薄膜中的分布是随机的,其直径在1.6~15 nm内.根据晶体生长理论和计算机模拟,讨论了升温快慢与所形成纳米硅颗粒大小之间的关系,并且在强光照射下观察了纳米晶硅在薄膜中的结晶和生长情况.经退火形成的nc-Si可见光辐射较弱,不能检测到它们的光致发光,但用氢氟酸腐蚀钝化后则可检测到较强的红PL,并且钝化后的nc-Si在空气中暴露一定时间后,其辐射光波长产生了蓝移.就表面钝化和量子限制对可见光辐射的重要性作了讨论.  相似文献   

13.
<正> 尽管过去几年对非晶半导体多层膜及其界面对多层膜传输性能影响的研究甚多,然而对于界面缺陷态的特性及其密度了解甚少。不同的测量方法得到的a-Si:H/a-SiNx:H界面缺陷态密度可从1010变到1012cm-2。这一实验结果反映了每一测试方法仅能探测某些能级的缺陷,在某些情况下可能是不同类的缺陷。非晶硅系材料都包含有氢。已发现,在多层膜的沉积过程中,由于组成多层膜的子层间应力释放的需要以及两子层材料的氢扩散系数不同而  相似文献   

14.
讨论了影响非晶硅太阳电池稳定性的因素,介绍了改善非晶硅材料稳定性的方法,进行了非晶硅太阳电池光致衰减测试.描述了电流注入退火和热退火对非晶硅太阳电池性能的改善.  相似文献   

15.
We propose fluorinated silicon oxide (SiOF) as the ion-stopper of bottom-gate amorphous silicon thin film transistors (a-Si:H TFTs). The low dielectric constant SiOF on both the back-channel of the TFT and the crossover regions of gate/data lines can contribute to reducing the RC delay of the gate pulse signal in active-matrix liquid-crystal displays. Besides, the a-Si:H TFT with a SiOF stopper shows an improved performance compared to the widely-employed silicon nitride (SiNx ) stopper TFT, because the fluorine incorporation reduces the interface state density between a-Si:H and SiOF  相似文献   

16.
We have developed a novel, low off-state leakage current polycrystalline silicon (poly-Si) thin-film transistor (TFT) by introducing a very thin hydrogenated amorphous silicon (a-Si:H) buffer on the poly-Si active layer. The a-Si:H buffer is formed on the whole poly-Si and thus no additional mask step is needed. With an a-Si:H buffer on poly-Si, the off-state leakage current of a coplanar TFT is remarkably reduced, while the reduction of the on-state current is relatively small. The poly-Si TFT with an a-Si:H buffer exhibited a field effect mobility of 12 cm2/Vs and an off-state leakage current of 3 fA/μm at the drain voltage of 1 V and the gate voltage of -5 V  相似文献   

17.
We have fabricated a high performance polycrystalline silicon (poly-Si) thin film transistor (TFT) with a silicon-nitride (SiNx ) gate insulator using three stacked layers: very thin laser of hydrogenated amorphous silicon (a-Si:H), SiNx and laser annealed poly-Si. After patterning thin a-Si:H/SiNx layers, gate, and source/drain regions were ion-doped and then Ni layer was deposited. This structure was annealed at 250°C to form a NiSi silicide phase. The low resistive Ni silicides were introduced as gate/source/drain electrodes in order to reduce the process steps. The poly-Si with a grain size of 250 nm and low resistance n+ poly-Si for ohmic contact were introduced to achieve a high performance TFT. The fabricated poly-Si TFT exhibited a field effect mobility of 262 cm2/Vs and a threshold voltage of 1 V  相似文献   

18.
This paper presents the results of a systematic study on the effects of stress on aluminum-induced crystallization (AIC) of plasma-enhanced chemical-vapor-deposited (PECVD) amorphous silicon (a-Si:H). To decouple the impact of stress on the AIC of a-Si:H from other factors that may affect crystallization, such as a-Si:H and aluminum deposition conditions, identical thin film structures [Al (200 nm)/a-Si:H (200 nm)] were deposited on the front surface of all samples. On the back surfaces, various amorphous silicon films were deposited to adjust the curvature of the samples and, therefore, the stress in the a-Si:H film on the front surface. It was found that tensile stress in a-Si:H can retard the AIC of a-Si:H.  相似文献   

19.
马铁英  李铁  刘文平  王跃林 《半导体学报》2008,29(11):2265-2269
用PECVD技术制备了不同掺磷比的非晶硅薄膜,然后退火改性.红外透射光谱揭示了薄膜内部的键合模式随生长工艺条件变化的规律;测量和分析了非晶硅红外热吸收及电阻温度系数与薄膜结构之间的关系.综合考虑非晶硅电阻率和电阻温度系数两个因素,采用掺杂比0.025,退火温度600℃的薄膜样品进一步研究.  相似文献   

20.
本文报道了用于平板液晶显示(LCD)的氢化非晶硅薄膜晶体管(α-Si:H TFT)的研制结果,此晶体管开态电流约10~(-6)A,关态电流<10~(-11)A,开启电压~15V.用此α-Si:H TFT矩阵已封装出具有20×20个有效象素单元的液晶显示平板,并成功地实现了有源选址与动态显示功能.同时,对如何进一步提高TFT性能作了一些分析与讨论.  相似文献   

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