Laser enhanced epitaxial growth of gallium arsenide from elemental arsenic
Metalorganic compounds and group V hydrides absorb strongly in the far ultraviolet region. The metalorganic vapor phase epitaxial (MOVPE) growth of gallium arsenide (GaAs) can be enhanced by irradiation with a laser of appropriate wavelength. To alleviate the hazard associated with arsine, the commonly used group V source for MOVPE of GaAs, elemental As has been used in this work. Elemental arsenic is believed to be the best alternate As source for most applications; organoarsenic compounds (such as tertiarybutylarsine), though of scientific interest, are unlikely to be used for epitaxial GaAs production because of their extremely high costs. The use of ArF excimer laser (193 nm) has been found to enhance the epitaxial growth of GaAs from As and triethylgallium (TEGa). The epitaxial temperature is reduced, and the growth rate is increased. The extent of enhancement depends strongly on the laser fluence. The grownfilms ] are usuallyn-type with a room temperature net carrier concentration of (1-6) x 1015 cm-3; however, mobility measurements indicated a high degree of compensation, particularly in films grown under high fluences. Epitaxial GaAs films grown with high laser fluence have also been found to have high carbon concentration from photoluminescence measurements, due presumably to the dissociation of C-C and C-H bonds in TEGa. This type of material may not be suitable for certain minority carrier devices.