Interfacial Reaction Analysis of Cu-Sn-Ni-P/Cu Joint Using Microwave Hybrid Heating

Microwave hybrid heating (MHH) technique was used to investigate the formation of intermetallic compound layer at Cu-7.0Ni-9.3Sn-6.3P/Cu interface. Two different susceptor materials; graphite and silicon carbide were used to provide initial heating of the filler alloy before it starts couple with the microwaves and melted on the Cu surface. The interface of IMC layer was characterized using Scanning Electron Microscope (SEM), energy dispersive X-ray spectrometry (EDS) and microhardness. Metallurgical study showed the formation of the IMC layer with multiphase at the joint interface for microwave heating of both susceptor materials. The thickness of IMC layer heating in silicon carbide susceptor was three times thinner than heating in graphite susceptor; 16.5 μm and 50.5 μm, respectively. The findings showed that microwave hybrid heating can be used to join Cu-7.0Ni-9.3Sn-6.3P/Cu and controlled the thickness of IMC layer.

A Kind of Coating Method of GaN-MOCVD Graphite Susceptor

A novel coating method for the GaN-MOCVD graphite susceptor is proposed in the paper, which means that the upper surface and sides of the graphite susceptor are covered with a low emissivity material coating, and the surface under the susceptor is covered with a high emissivity SiC coating. By using finite element analysis software COMSOL Multiphysics, the temperature field of the susceptors without coating, with common SiC coating, and with improved coating is obtained and compared, which shows that the susceptor with the improved coating not only increases the heating efficiency of the heater, but also improves the temperature uniformity of the substrate, which can be of great benefit to the film growth. In addition, this improved coating for the susceptor has the same heating sensitivity as the common SiC coating.

Numerical Simulation of the Effects of Different Coatings on Graphite Susceptor for the Induction Process of Polycrystalline Silicon

The vacuum induction melting and control solidification is a new developed process for the manufacture of polycrystalline silicon with the advantage of quick heating rate compared to the traditional resistance heating method. The graphite susceptor of the induction furnace plays a key role in controlling the temperature of the melt of polycrystal silicon for solar cells. This paper investigates how different coatings painted on the susceptor would influence the heating efficiency and the temperature distribution of the silicon melt. A graphite susceptor is usually coated with a thin film of insulating material to reduce heat losses and to prevent vapors such as SiO to contaminate the susceptor. Numerical simulations show that the coating material at the outer surface of the susceptor should be the one with low thermal conductivity to prevent heat loss. On the other hand, the coating on the inner surface should be the material with high thermal conductivity to allow easy heat transfer.

Modelling the Effects of Material Property and Dimension on the Heating of Silicon with Induction Directional Casting Furnace

Directional Casting of silicon is a cost effective process to grow multi-crystalline Si ingots for wafers of solar cells. An appropriate melting process of polycrystalline silicon is closely related to the material properties and the size of graphite susceptors. These parameters have great influence not only on the melting temperature of silicon melt but also on the efficiency of induction heating, impurity distribution, dendrite and the direction of crystalline grains, which ultimately affect the properties of the solar cells. Therefore, in order to obtain good quality and energy efficiency of growth of polycrystalline silicon, one needs to know how the temperature fields relate to the processing parameters such as different sizes and properties of graphite susceptors in the furnace. In this paper, the influences of different properties such as density, electrical conductivity, thickness of graphite susceptor and cooling base-plate on the temperature of silicon with induction heating have been studied. To have an optimized control of processing parameters, a finite element-based software was used to simulate the temperature distribution of silicon melt in a polycrystalline vacuum induction refining furnace. The simulation takes into account the interaction of the induced eddy current and the heat transfer coupling in the vacuum induction furnace. Some of the modelling results are summarized as follows: 1. The material properties of the graphite susceptor have great influence on the temperature distribution. 2. The higher the operating frequency of the current, the sooner it reaches the melting temperature. 3. Base-plate made of stainless steel 304 performs better than the copper base-plate for the control of temperature distribution. 4. There exists an optimal thickness of the graphite susceptor, and the rise of temperature is not linearly proportional to the thickness of the graphite susceptor.

Long Carrier Lifetime in 4H-SiC Epilayers Using Chlorinated Precursors

In this work we report the measurement of minority carrier lifetimes using the time resolved photoluminescence technique. It was found that 4H-SiC homo-epilayers grown using chlorine-based precursors have longer carrier lifetimes if used in conjunction with a tantalum carbide coated (TaC-coated) graphite susceptor rather than a SiC-coated graphite susceptor. Longer carrier lifetimes were obtained by optimal combinations of precursor gases and susceptor type. The controllable variation in lifetime from 250 ns to 9.9 s was demonstrated.

Numerical Simulation of RF Heating for a SIC Vapor Growth System

A numerical model has been developed to calculate the magnetic potential and temperature distribution in a RF heating system used for a SiC vapor growth system. The magnetic vector potential is calculated by solving the Maxwell equations. The heating power generated in the graphite susceptor is obtained using the Joules law. The temperature profile in a growth chamber is then calculated by solving the energy transport equation with induction heat as a source term. Two sets of grid system have been used to speed up the calculation. The frequency of RF heating and coil current are found to have significant impact on heat generation and its distribution in the graphite susceptor. The maximum temperature in the crucible has a linear relationship with the input power; however, the power input does not influence significantly the temperature gradient. To optimize the heating system for a SiC vapor growth system, the current, frequency, and geometry need to be carefully designed.