Epitaxy process

Molecular beam epitaxy is a non-CVD epitaxial process that deposits silicon through evaporation. MBE is becoming more common as commercial equipment becomes available. In essence, silicon is heated to moderate temperature by an electron beam in a high vacuum... 

Fig. 13. Furnace reactor for the growth of HgCdTe films on CdZnTe substrates usiag the Hquid-phase epitaxial process. The melt is tellurium ia a quartz...

Once the thermodynamic parameters of stable structures and TSs are determined from quantum-chemical calculations, the next step is to find theoretically the rate constants of all elementary reactions or elementary physical processes (say, diffusion) relevant to a particular overall process (film growth, deposition, etc.). Processes that proceed at a surface active site are most important for modeling various epitaxial processes. Quantum-chemical calculations show that many gas-surface reactions proceed via a surface complex (precursor) between an incident gas-phase molecule and a surface active site. Such precursors mostly have a substantial adsorption energy and play an important role in the processes of dielectric film growth. They give rise to competition among subsequent processes of desorption, stabilization, surface diffusion, and chemical transformations of the surface complex. 

An imager is presented in JP-A-62071270 in which HgCdTe layers are grown directly on a read-out substrate by an epitaxial process. 

Cyclopentadienyl compounds have been thoroughly investigated as suitable precursors to rare earth doped semiconductors in MOCVD (metal-organic chemical vapor deposition) or MOVPE (metal-organic vapor phase epitaxy) processes [283]. The use of btsa complexes for the same purpose has appeared in the literature very recently [285]. Typical process conditions are shown in Scheme 14. It was found that the carbon contamination of the deposited metal is less in the btsa case. 

However, in Manasevit s first paper on MOCVD, concerning the epitaxial growth of GaAs on insulators, the actual epitaxial process was not even mentioned ... 

Low solubility of solvent into the silicon During epitaxial process, atoms of the solvent are incorporated in the Si crystal. Their incorporation can modify the electronic properties of the layer. Actually, many metallic impurities act as recombination centre or as dopant and reduce the lifetime of minority carriers. Solvent purity is also an important parameter to avoid other impurities. 

The presence of hydrogen chloride in the gas phase implies that the epitaxial process results from a balance between growth and etching. 

The modern microelectronics and semiconductor industries have imposed severe demands on the quality of films produced by the silicon epitaxy process and the epitaxial film deposition techniques need to fulfill several general... 

SIMOX and Unibond wafers require epitaxy to increase the thickness of the top layer. An epitaxial layer up to 60 pm thick can be grown on such wafers the resulting thickness tolerance depends on the epitaxy process tolerances and is typically in the range of 5% of the final thickness (4a value). 

Vainshtein et al [5] and Dmitriev et al [6] described the first SiC dynistor diode. This diode is an n-p-n-p thyristor-like structure but without gate contacts. For this device, an n-p+-n+ structure was epitaxially grown on a p+ 6H-SiC substrate using container-free liquid phase epitaxy in a continuous epitaxial process. The contacts were made from Al. The turn-on time constant varied from 1 ns to 10 ns. The recovery time varied from 150 to 200 ns. The static switching voltage varied between 10 V and 50 V with an inverse voltage of up to 90 V. Recently, Edmond et al [7] have fabricated the first a-SiC thyristor which operated up to 350 °C. 

In the last years it became possible to manufacture silicon SPADs in standard epitaxial processes as they are used for high-speed CMOS devices [117, 245, 246, 354, 424, 459]. The diodes are characterised by a small thickness of the depletion region. The thin depletion region results in a relatively low breakdown voltage, high time resolution, and low dark count rate. The drawback of the thin depletion region is a reduced quantum efficiency in the near infrared. Laser pulses recorded with an id 100-20 SPAD detector of id Quantique [245] and an SPC-144 TCSPC module of Becker Hickl are shown in Fig. 6.57. 

Wafer shape evaluation before and after film deposition and epitaxial processes... 

There are, however, some a priori arguments which favour non-epitaxial processes as the major mechanism of oriented overgrowth of biominerals from ion precipitation at organic surfaces. Firstly, epitaxis requires a rigid two-dimensional atomic net whereas non-epitaxial deposition can be achieved from a more flexible surface on which there are specific molecular configiirations of polypeptide side chains. For example, it has been suggested that the deposition of apatite within the 640 A ( hole ) zones between colla-... 

Many deposition methods are available for fabricating semiconductor electrodes. However, each technique has advantages and drawbacks that should be kept in mind when choosing a fabrication method. For instance, monocrystaUine materials with high PEC performance can often be obtained via molecular epitaxy processes. 

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