Vapor phase epitaxy reactor

It is clear that the development of vapor phase epitaxy reactor at atmospheric pressure is booming. The process leads to good quality material and is compatible with the photovoltaic industry criteria of efficiency and reduced production costs. Indeed, the active layer deposition step represents the main cost of a thin cell process. Any innovation to reduce the thermal budget of this operation is of major interest. 

D.I. Fotiadis, S. Kieda, and K.F. Jensen. Transport Phenomena in Vertical Reactors for Metalorganic Vapor Phase Epitaxy I. Effects of Heat Transfer Characteristics, Reactor Geometry, and Operating Conditions. J. Cryst. Growth, 102 441—470,1990. 

There are several technologies for creating the conditions inside a reactor needed to support epitaxial growth, of which the most important is Vapor Phase Epitaxy (VPE). In this process, a number of gases are introduced in an induction heated reactor where only the substrate is heated. The temperature of the substrate typically must be at least 50 % of the melting point of the material to be deposited. 

The diffusion of Mg was studied in GaN layers grown onto sapphire substrates by atmospheric-pressure metalorganic vapor-phase-epitaxy in a so-called home-made reactor. Secondary ion mass spectroscopy was used to visualize the Mg profiles in 2 types of multi sub-layer GaN structures. One structure was grown with a variable flow of Ga precursor, and the other with a variable growth temperature. In both cases, the Mg dopant precursor (Cp2Mg) flow was constant. Using Pick s second law to fit... 

A-plane GaN films with different thickness between 1 [im and 67 [im were grown on r-plane sapphire by metal-organic vapor phase epitaxy (MOVPE) and HVPE. The a-plane MOVPE films were grown at University of Stuttgart and University of Bremen at 1030-1050 °G using a conventional two-step process employing GaN or AlN buffer layers [45, 46]. The a-plane HVPE films were grown at University of California, Santa Barbara, directly on sapphire in a three-zone horizon reactor at 1040-1070 °C [47]. 

The epitaxy reactor is a specialized variant of the tubular reactor in which gas-phase precursors are produced and transported to a heated surface where thin crystalline films and gaseous by-products are produced by further reaction on the surface. Similar to this chemical vapor deposition (CVE)) are physical vapor depositions (PVE)) and molecular beam generated deposits. Reactor details are critical to assuring uniform, impurity-free deposits and numerous designs have evolved (Fig. 22) (89). 

The CVD method involves a chemical reaction in a vapor phase which results in deposition of a solid on a heated surface. Various PVD processes such as ion plating, sputtering, molecular beam, evaporation, and epitaxy might be also included in CVD processes [112]. The various CVD methods are powerful processes used for the fabrications of a wide variety of thin-film materials including solar cell materials and semiconductor materials for electronic applications, as well as the manufacture of coatings, powders, fibers, and monolithic components. There are two types of CVD reactors, the differential reactor and the starved reactor, according to the value of the flow rate (F,) defined as... 

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