Selective area metalorganic vapor phase epitaxy growth of prism-shaped GaAs resonators for folded cavity surface emitting lasers

Selective area (SA) metalorganic vapor phase epitaxy (MOVPE) proves to be a n effective method of manufacturing nonplanar structures with precisely con trolled sizes and orientations of their facets. Excellent flatness of the f acets makes SA MOVPE especially useful for optoelectronic applications such as microcavities. In this work we use this technique to grow prism-shaped GaAs cavities for novel prismatic (folded) cavity surface emitting laser di odes. Design of these devices has been recently proposed. Critical points i n growing the cavities are: (i) to ensure 90 degrees angle at the top of th e prism, (ii) to obtain flat walls of the GaAs prism (4 mu m wide at the ba se) with the sharp top, (iii) to avoid an excessive number of polycrystalli ne precipitates on the surface of a dielectric mask (SiO2 100 nm thick) des pite the very disadvantageous ratio of openings to whole substrate area. Gr owth-rate calculations have been performed using total area of mask opening s as an active substrate surface. For proper prism growth the pulsing epita xy technique using Aixtron MOVPE LP system was applied, where interruption growth periods which enabled efficient surface molecules migration into ope nings. Optimization of the growth/interruption time versus partial pressure of gallium was essential for laser application to obtain suitable shape of the prisms. The best results for 2 mu m high prisms were obtained for 272 pulses of 2 s growth/3 s interruption, when total pressure and temperature were 100 mbar and 700 degrees C, respectively. (C) 1998 Elsevier Science B. V. All rights reserved.