Reaction Chemistry of ZnTe Metalorganic Vapor-Phase Epitaxy

Abstract

The reaction chemistry of zinc telluride (ZnTe) metalorganic vapor-phase epitaxy (MOVPE) from dimethylzinc (DMZn), diethylzinc (DEZn), and diisopropyltelluride (DIPTe) has been studied using on-line gas chromatography and infrared spectroscopy. Two growth regimes have been discovered: one at low values of the II/VI ratio and the other at higher values of the II/VI ratio. In the first regime, the group VI compound is consumed in excess, while in the second regime, the group II compound is consumed in excess. The crossover point lies at II/VI ) 5.0 for DMZn and at II/VI ) 0.3 for DEZn. Stoichiometric ZnTe is deposited under all growth conditions. The excess DIPTe consumed is converted into volatile diisopropylditelluride and isopropyltellurol. Conversely, the excess DEZn or DMZn consumed produces zinc metal. These waste byproducts accumulate in the outlet of the reactor. The hydrocarbon products generated from the ethyl and isopropyl ligands are indicative of radical disproportionation, recombination, and hydrogenation reactions. However, the methyl ligands mainly undergo surface hydrogenation to produce methane.

Comparative study of diethylzinc and dimethylzinc for the growth of ZnO

“…In contrast, only the ZnO phonon modes were observed in curve (c) for the as-grown sample with DEZn, without any additional modes related to carbon or hydrogen. The primary reason is the different reaction pathways of methyl and ethyl, where ethyl groups formed from DEZn were desorbed via b-hydride elimination process [12]. Thus, we can conclude that the content of carbon and hydrogen in the DMZn grown film is much higher than that in ZnO grown with DEZn.…”

“…Vohs et al have studied the surface reactions and adsorptions of DEZn and DMZn on Si (1 0 0) and GaAs (1 0 0) templates in comparison by means of temperature programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS) [8][9][10][11]. The reaction chemistry of ZnTe MOVPE using DMZn and DEZn has also been studied in detail by Wilkerson [12]. However, our understanding of the effect of DEZn and DMZn on the growth of zinc oxide and related electrical and optical properties is not nearly complete, and few comparisons of these zinc precursors are recently shown to influence the fundamental properties of ZnO.…”

Effects of Ligand Exchange Reactions on the Composition of Cd1-yZnyTe Grown by Metalorganic Vapor-Phase Epitaxy

“…The experimental apparatus and procedures used for this study have been described previously in detail. , An atmospheric-pressure MOVPE reactor was used to deposit Cd 1 - y Zn y Te on the inner walls of a glass tube. The electronic-grade sources, DMCd, DMZn, DEZn, and DIPTe, were contained in 200 cm 3 stainless steel bubblers immersed in thermal regulating baths at 273, 258, 288, and 306 K, respectively.…”

“…Using on-line infrared spectroscopy, the consumption rates of the organometallic compounds were determined …”

Preparation of zinc containing materials

“…12 It has been suggested as a useful material in optoelectronic and thermoelectric devices, such as; in tandem solar cells, a buffer layer for a HgCdTe infrared detector, or as part of the graded p-Zn(Te)Se multiquantum-well structure in a blue-green laser diode. [13][14][15] An extensive literature exists detailing the synthesis and properties of zinc oxide (ZnO) thin films and nanostructures. Zinc oxide is a wide band gap material (3.37 eV), with a high exciton binding energy (60 eV), which ensures efficient excitonic ultraviolet (UV) emission at room temperature.…”