Application of tungsten films for substrate masking in liquid phase epitaxial lateral overgrowth of GaAs

Abstract

Liquid phase epitaxial lateral overgrowth of GaAs layers on GaAs substrates masked by tungsten films was studied. We show that at our growth conditions perfect growth selectivity was obtained, so the layers started growing from the openings cut in the mask only. However, serious damage of the mask during epitaxial growth was observed. As this deteriorates crystallographic quality of the layers a procedure was elaborated to eliminate degradation of the tungsten film by the melt. In particular, reduction of growth temperature and deposition of Au/Zn wetting layers between tungsten film and the GaAs substrate were found important to avoid degradation of the mask and for successful lateral growth of the layers. Tungsten masked GaAs substrates were then used for lateral overgrowth of GaAs by liquid phase electroepitaxy. Preliminary results are presented showing that application of electrically conductive tungsten mask, which allows a direct DC current flow from the melt to the substrate, results in much wider and thinner electroepitaxial layers than those grown on the substrates coated by insulating film.

Recent progress in lateral overgrowth of semiconductor structures from the liquid phase

“…SiO 2 ) is nearly isotropic despite surface kinetic processes favouring faceting of upper ELO surface. Consequently, a dome-shaped ELO layer is obtained in agreement with our experimental observation [28]. Situation is quite different however, if electrically conductive film is used to mask the substrate.…”

“…We have experimentally studied growth of GaAs ELO layers on GaAs substrates by LPEE [28]. Significant enhancement of lateral overgrowth has been found for substrates masked by electrically conductive (tungsten) mask as compared to the layers grown under the same conditions on substrates masked by insulating SiO 2 films.…”

“…Recently, there is also an increasing interest in lateral overgrowth of semiconductor layers by the liquid phase electroepitaxy (LPEE) technique [26][27][28]. In this method layer crystallisation is achieved by passing an electric…”

Properties of ZrN films as substrate masks in liquid phase epitaxial lateral overgrowth of compound semiconductors

“…SiO 2 and Si 3 N 4 ) are commonly used for substrate masking in ELO, but they are electrical insulators. In our previous paper [5] we reported the application of ____________________ * Corresponding author: e-mail: Zbigniew.Zytkiewicz@ifpan.edu.pl tungsten film for substrate masking in lateral overgrowth of GaAs. Perfect growth selectivity was obtained for such a system.…”

A model for epitaxial lateral overgrowth of GaAs by liquid-phase electroepitaxy

“…Recently, there is also increasing interest in lateral overgrowth of semiconductor layers by the liquid-phase electroepitaxy (LPEE) technique [22][23][24]-a solution growth method in which layer crystallization is achieved by passing an electric current through the solid-liquid interface while the furnace temperature of the system is kept constant. The LPEE process is quite complex and involves the interactions of various thermomechanical, electromagnetic, and chemical phenomena [25][26].…”