大直径直拉硅单晶中的空洞型原生缺陷

空洞型 ( Void)原生缺陷在大直径直拉硅单晶中的重要性日渐突出。本文在论述大直径硅单晶中 Void缺陷基本性质的同时 ,详细综述了这类缺陷的控制方法以及它与轻元素 (氧、氮、碳、氢 )杂质的相互作用 ,并简要讨论了关于 Void缺陷的研究方法和今后的研究方向。     

直拉硅中氧沉淀的TEM研究

论述了使用透射电镜来研究氧沉淀的形态与热处理温度和时间的关系.对氧沉淀的生成动力学,研究的现状和存在的问题以及发展前景也进行了讨论.     

Detection of oxygen concentration in silicon wafers using a tunable diode laser

Control of the oxygen concentration in silicon wafers is important for the fabrication of high quality integrated circuits. Techniques for the fast detection of oxygen would be desirable for production line quality control. The oxygen concentration in silicon has traditionally been measured by a Fourier transform infrared spectrometer (FTIS). Due to the slow response time (1-10 min), it is not suitable for wafer screening. In this report, we describe a diode laser spectroscopy technique for the fast (10 ms) detection of oxygen in production line silicon wafers. The results are in good agreement with those measured by the Fourier transform technique.     

Interpretation of a non-conventional reverse-current curve of a depletion-type gate-controlled diode

This work deals with the reverse-current characteristics of an nMOS gate-controlled diode with an implanted N type layer at the surface of the channel. Two possible forms of the characteristics curve, which can be obtained depending on the final material quality (lifetime and surface generation velocity) and on the silicon surface doping level, are discussed. An experimental nonconventional curve and its interpretation are presented. An estimated surface generation velocity was calculated by means of Pierret's correction procedure and a value of approx. 1 cm/sec was obtained.     

Determination of Si-SiO2 interface recombinationparameters using a gate-controlled point-junction diode underillumination

A novel method is presented to determine Si-SiO₂ interface recombination parameters. The device used is a polysilicon-oxide-semiconductor capacitor with a microscale central junction (a gate-controlled point-junction diode). Data analysis has been performed using a numerical scheme to find a quasi-exact solution for the current combining at the interface. It was found that the interface recombination parameters depend only weakly on trap energy in a wide range around midgap. The cross-section for capturing electrons was found to exceed the cross-section for capturing holes by a factor of 10² to 10³     

Modulation of millimeter-waves using diode laser illumination of a silicon waveguide

A quantitative study of the phase and/or amplitude modulation of millimeter-waves by a diode laser is reported. Using millimeter-waves as a probe, the transport properties of an optically induced electron-hole plasma in a bulk silicon waveguide may be measured. A theoretical model has been developed to predict the temporal behavior of the plasma in the case of low level optical injection. This model agrees well with the measured data.     

Strains and crystal lattice defects arising in macroporous silicon under oxidation

The deformation behavior of a macroporous silicon wafer subjected to high-temperature oxidation has been studied, and the basic parameters describing the sample bending and subsequent stress relaxation when oxide is removed are determined. X-ray diffractometry and topography were used to determine the sample bending radius and lattice parameters, and to reveal the areas of dislocation generation. The strain of a silicon lattice in oxidized macroporous Si is about 10^?4, and it decreases by an order of magnitude after oxide dissolution. The plastic part of the strain is accompanied by the generation of dislocations in the most strained regions of a structure, i.e., at the interfaces between the porous layer and substrate in the vertical direction and between the central porous region and the pore-free edge in the horizontal plane. The dislocation density is ～10⁴ cm^?2.     

Electrical and optical characterization of p-type ZNSe for diode laser structures

The doping properties of nitrogen in ZNSe to produce p-type material have been explored by photo-assisted molecular beam epitaxy. These prelimiN_Ary results show that changes in N_A - N_D with ultraviolet irradiation are due to the effect of the laser on the selenium aN_D so far no primary photoeffect has been observed. Photoluminescence measurements on the ZNSe:N layers show the presence of a second donor-acceptor pair recombination due to deep donors that has been assigned to V_Se-N_Se pairs. The change in carrier concentration profile with time for ZNSe:N supports the involvement of a N_Ative defect in the compensation process. ZnCdSe/ZNSe quantum well laser diodes have been fabricated showing blue emission at 475 nm.     

Microstructural examination of extended crystal defects in silicon selective epitaxial growth

Selective epitaxial growth has been used to produce electronically isolated devices. The oxide/silicon interfaces in such materials are often associated with regions of poor device performance. In this study, the extended defects in the bulk near interfacial regions are examined by transmission electron microscopy. Process modifications suggest a large portion of the defects were due to thermal expansion mismatch and can be avoided.     

Study of the potential distribution in a forward-biased silicon diode using electrostatic force microscopy

Electrostatic force microscopy was used to study the potential distribution in a forward-biased epitaxial-diffused n ⁺-n-p-p ⁺ silicon diode. Distributions of potential and capacitance were determined across the cleaved surface, which intersected the layers in the diode structure. Variations in the surface potential and capacitance were preliminarily measured with a submicrometer spatial resolution and were used to determine the position and width of the n-p junction; the distribution of applied forward bias in the diode was also assessed. It is shown that an additional potential barrier for injected charge carriers may exist in the vicinity of the n ⁺-n junction in the diode under consideration. For an injection-current density exceeding 100 mA/cm², the voltage drop across this barrier becomes comparable with the voltage variations across the operating n-p junction.     

Characterization of structural defects in the silicon crystal grown with various seeds

To see the effect of the seeds on the crystallization of the silicon ingot, two types of seed were prepared and applied to the mono-like multi-crystalline silicon crystallization. One of them was conical shaped seed divided vertically into 4 pieces and the other one was chipped silicon seeds. Both of the seeds were placed at the bottom of the crucible before the growth of the multi-crystalline silicon material with a conventional directional solidification process. Compared to the conventional thin and flat seeds, conical shaped seed result in the larger single crystalline portion in the ingot although the gap of the seed division might act as source of dislocation generation during the crystal growth. This was expected to be due to the lateral growth of the silicon single crystalline grown from the conical seed which is taller than normal flat seeds. And also, comparison of the Minority Carrier Life Time (MCLT) between the silicon crystal grown from the chipped silicon seeds and the silicon crystal grown without any seed was conducted. It was found that the silicon crystal grown with chipped silicon seeds shows higher MCLT than the silicon crystal grown without seeds, although both crystals look similar as multi-crystalline silicon.     

Correlation of the leakage current and charge pumping in silicon oninsulator gate-controlled diodes

The leakage and charge pumping currents were measured in gate-controlled MOS p-i-n diodes fabricated on thin SIMOX substrates. The efficiencies of the techniques as well as their complementary features are analyzed for various experimental conditions. The interface properties of device-grade SIMOX wafers are characterized and shown to be compatible with VLSI requirements. Special interface coupling effects, which occur only in fully depleted SOI devices and modify the conventional signature of charge pumping and leakage current, are thoroughly investigated     

Growth and crystal quality of inp crystals by the liquid encapsulated czochralski technique

The growth of InP single crystals by the liquid encapsulated Czochralski (LEC) technique has been studied from the standpoint of improving crystal quality. Twin-free crystals have been grown reproducibly in the <lll>P direction under the following conditions; (1) using starting material which does not contain fine InP particles, (2) controlling the cone shape of the crystals such that the angle with the growth axis is less than 19.68°, (3) arranging the.hot zone to produce a temperature at the top surface of the B₂O₃ encapsulant layer below 550°C. It has been confirmed that electrical properties of nominally undoped crystals are dominated by the impurity, Si, and the concentration of Si in an LEC crystal corresponds to that of the starting material. The dislocation densities of undoped LEC InP crystals depend on thermal stresses during the growth process. This knowledge has led to the growth of dislocation-free crystals.     

Electrical characterization and modelling of high energy pre-amorphized PN silicon junctions

Shallow P⁺N junctions were obtained using germanium pre-amorphization step to reduce the high diffusivity of boron implanted in silicon. The germanium implantation step was performed under different conditions of temperature: ambient temperature and nitrogen temperature. P-type doping was obtained by boron implantation at relatively low energy. To characterize and simulate the electrical behaviour of such samples, steady state current-voltage measurements have been performed at different temperatures varying between 172 and 294 K. The results show a close dependence between the current-voltage characteristics of the samples and their technological parameters of manufacturing. The pre-amorphization step at ambient temperature seems to improve the electrical behaviour of the junction. To simulate the electrical characteristics of the studied samples, a reliable model has been developed based on the classical Spice formulas and taking into account additional phenomena. The simulated curves satisfactorily fit the experimental results for all the samples.     

Large-signal analysis of a silicon Read diode oscillator

This paper presents theoretical calculations of the large-signal admittance and efficiency achievable in a silicon p-n-v-ns Read IMPATT diode. A simplified theory is employed to obtain a starting design. This design is then modified to achieve higher efficiency operation as specific device limitations are reached in large-signal (computer) operation. Self-consistent numerical solutions are obtained for equations describing carrier transport, carrier generation, and space-charge balance. The solutions describe the evolution in time of the diode and its associated resonant circuit. Detailed solutions are presented of the hole and electron concentrations, electric field, and terminal current and voltage at various points in time during a cycle of oscillation. Large-signal values of the diode's negative conductance, susceptance, average voltage, and power-generating efficiency are presented as a function of oscillation amplitude for a fixed average current density. For the structure studied, the largest microwave power-generating efficiency (18 percent at 9.6 GHz) has been obtained at a current density of 200 A/cm², but efficiencies near 10 percent were obtained over a range of current density from 100 to 1000 A/cm².     

Electrical characterization of defects introduced during metallization processes in n-type germanium

We have studied the defects introduced in n-type Ge during electron beam deposition (EBD) and sputter deposition (SD) by deep-level transient spectroscopy (DLTS) and evaluated their influence on the rectification quality of Schottky contacts by current–voltage (I–V) measurements. I–V measurements demonstrated that the quality of sputter-deposited diodes are poorer than those of diodes formed by EBD. The highest quality Schottky diodes were formed by resistive evaporation that introduced no defects in Ge. In the case of EBD of metals the main defect introduced during metallization was the V–Sb complex, also introduced during by electron irradiation. The concentrations of the EBD-induced defects depend on the metal used: metals that required a higher electron beam intensity to evaporate, e.g. Ru, resulted in larger defect concentrations than metals requiring lower electron beam intensity, e.g. Au. All the EBD-induced defects can be removed by annealing at temperatures above 325 °C. Sputter deposition introduces several electrically active defects near the surface of Ge. All these defects have also been observed after high-energy electron irradiation. However, the V–Sb centre introduced by EBD was not observed after sputter deposition. Annealing at 250 °C in Ar removed all the defects introduced during sputter deposition.     

Thermal noise of a silicon double-injection plasma diode

Measurements of the thermal noise of a silicon p⁺−π−n⁺ diode operating in the Lampert-insulating regime agree within 6 per cent with the prediction S_i = 4kT Re(Y). The noise measurements were performed in the cube-law regime with d.c.-currents from 100 μA to 4mA at room temperature.     

Demonstration of a tunable hybrid laser diode using anelectrostatically tunable silicon micromachined Fabry-Perotinterferometer device

A previously reported silicon micromachined Fabry-Perot interferometer device is used for the first time with an edge-emitting single-quantum-well high-power laser diode in an extremely short external cavity configuration to realize a tunable laser diode. This hybrid configuration is advantageous in that it allows the use of “off-the-shelf” components, loose adjustment tolerances and potentially has low cost. In the current demonstration, external optical feedback from the extremely short-external-cavity, formed by such hybridization of the laser diode and the micro-optoelectro-mechanical device, resulted in a 4-nm range of quasi-continuous tuning with tens of milliwatts of output power     

Electrical polarization control of vertical-cavity surface-emittinglasers using polarized feedback and a liquid crystal

We report electrical control of the polarization state of a vertical-cavity surface-emitting laser (VCSEL), The VCSEL is subject to strong external optical feedback (up to 6% of emission), with polarization controlled by a liquid-crystal (LC) element, It is found that the contrast ratio of the complete system can be enhanced compared to the contrast ratio of the LC element alone     

Influence of silicon crystal defects and contamination on the electrical behavior of power devices

Since power devices require a thick electrically active n-type silicon layer with high resistivity and a large area, their electrical characteristics are extremely sensitive to contamination. If heavy metals diffuse into the silicon wafers during the high-temperature steps, an uncontrolled increase in the leakage current and the on-state voltage can be observed. Furthermore, current filamentation and instabilities of the electrical data can occur. It turned out that the optimization of the cleaning processes, high-temperature steps and gettering treatments alone is not sufficient to avoid such effects. It is also important to avoid silicon crystal defects by proper processing. A dramatic increase in the leakage current was correlated with the appearance of silicon defects decorated with heavy metals. As a consequence of the low doping level of the n-base, the blocking voltage and the failure rate due to cosmic radiation are sensitive to contaminating atoms acting as donors.