GAS-Phase Decomposition Kinetics of MOVPE Precursors in a Counterflow Jet Reactor
- PDF / 480,159 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 100 Downloads / 198 Views
GAS-PHASE DECOMPOSITION KINETICS OF MOVPE PRECURSORS IN A COUNTERFLOW JET REACTOR S.A. SAFVI AND T.J. MOUNTZIARIS Department of Chemical Engineering and Center for Electronic and Electro-optic Materials, State University of New York, Buffalo, NY 14260
ABSTRACT A new reactor for studying the purely homogeneous thermal decomposition of organometallic precursors used in the Metalorganic Vapor Phase Epitaxy (MOVPE) of semiconductors is presented. The idea is based on the use of a counterflow jet configuration
with one jet being heated and the other unheated. The heated jet contains pure carrier gas (typically hydrogen or nitrogen), while the unheated jet contains vapors of an organometallic species diluted in the same carrier gas. Under appropriate operating conditions, decomposition of the organometallic species takes place near the stagnation plane where the hot jet collides with the cool jet. Since the reactions occur in the gas phase and away from hot walls, purely
homogeneous kinetics can be obtained. Such a counterflow jet reactor was designed for studying the thermal decomposition of tertiary-butyl-arsine (TBA), t-C 4 H 9 AsH 2 , a very promising precursor for MOVPE of GaAs films. Two-dimensional finite element simulations of transport phenomena and kinetics have been used to identify optimal operating conditions. An experimental system was constructed and capillary-sampled mass spectroscopy at the stagnation plane was used to study the thermal decomposition of TBA in nitrogen at a total pressure of 252
Torr. Gas-chromatography of the effluent gas stream was employed for positive identification of the hydrocarbon byproducts. The results indicate the existence of two major decomposition routes: (1) A low activation energy pathway producing isobutane AsH, and (2) a higher activation energy, a-hydride elimination pathway producing isobutene and arsine. INTRODUCTION One of the major challenges in the development of compound semiconductor thin films for advanced electronic and opto-electronic devices has been the optimal design and operation of reactors suitable for growing such materials. Metalorganic Vapor Phase Epitaxy (MOVPE) has emerged as a very attractive technique due to its versatility and cost-effectiveness [1]. This
technique is chemical in nature and is based on the decomposition of precursor gases or vapors over a heated substrate resulting in the growth of a thin solid film. A lot of effort is currently being devoted by researchers in this field on the study of the chemical reactions underlying MOVPE of semiconductors [2]. A better understanding of the chemistry during MOVPE can
lead to accurate control of film properties, to increased reactor efficiency and to the development of new operating procedures for growing custom-made films and microstructures. It will also enable the development of predictive models of the MOVPE process, which can substantially reduce the time and cost associated with reactor scale-up by minimizing the required experimental trial and error [3]. Two types of reactions ty
Data Loading...
