Computer Simulation of the Metal Organic Chemical Vapor Deposition of CdTe
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COMPUTER SIMULATION OF THE METAL ORGANIC CHEMICAL VAPOR DEPOSITION OF CdTe S. KANG,*
T.J. JASINSKI,*
G.S. TOMPA**,
AND
*CreareInc., Etna Rd., Box 71, Hanover NH 03755; **EMCORE Corp., 35 Elizabeth Ave., Somerset, NJ 08873.
R.A. STALL**
ABSTRACT The optimization of chemical vapor deposition processes requires an understanding of the influence of various process parameters on the deposition of thin films. A recently developed computer simulation tool provides a powerful means to develop this understanding. This paper describes the use of the computer program, FLUENT, to study the gas flow, temperature, and chemical species distributions during the deposition of CdTe. Numerical results are reported for two operating conditions for an EMCORE vertical high-speed rotating disk growth reactor and are compared to experimental data. The influence of process parameters is discussed. The effects of the addition of significant amounts of Hg (several percent) to the process gas is evaluated.
INTRODUCTION The metalorganic chemical vapor deposition (MOCVD) growth of uniform high quality epitaxial films is of great importance to the compound semiconductor field. MOCVD has become the method of choice in the production of GaAs and InP based compound semiconductors and is making great strides with group IV and II-VI compound semiconductors as well as with oxides such as ferroelectrics and/or high temperature superconductors. The ability to optimize the deposition process requires an understanding of the interplay of gas flow, temperature, species distributions and reaction dynamics within the reaction chamber. To develop this understanding, detailed information about the transport processes within the reactor is required. This information can now be provided by a powerful simulation tool called FLUENT([]. A computational fluid dynamics (CFD) program, FLUENT has recently been expanded to include the modeling of CVD processes. This computer simulation tool provides a powerful means to realistically model CVD of thin solid films and to visualize how reactant and energy transport impact growth uniformity. In this paper we discuss this computer simulation tool and apply it to the modeling of CdTe growth. We chose to begin our work with CdTe so as to be in a position to address the more difficult HgCdTe growth problem. The addition of Hg will greatly effect the growth chemistry. The understanding of the impact of Hg on the growth is necessary for the successful MOCVD development of HgCdTe, which Is an important material for infrared detectors and Imaging arrays. There are two basic MOCVD growth reactor geometries used in the research and production of compound semiconductors. They are the horizontal tube and the vertical reactor with or without high-speed horizontal substrate rotation. The fundamental problem with the alloy growth of HgCdTe in a horizontal cell is the ability to maintain growth uniformity (thickness and composition). This is due to depletion of the Cd precursor from the growth stream along the reactor length. This i
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