Formation of AlxGa1−xAs periodic array of micro-hexagonal pillars and air holes by selective area MOVPE

Growth of GaAs/AlGaAs hexagonal pillars on GaAs (111)B surfaces by selective-area MOVPE

“…This is because slowly growing surfaces appear as facets in SA-MOVPE, and they are {110} surfaces in the present growth conditions [2]. Furthremore, due to the symmetry of (111) atm, the growth becomes inhomogeneous and pillar size, both diameter and height, becomes random when the growth temperature is raised to 850 • C. This is consistent with our previous results [5] and it is considered to be due to reevaporation and inhomogeneous nucleation of GaAs. Therefore, the results indicate that the re-evaporation is reasonably suppressed and by lowering the growth temperature.…”

“…The reason for the degradation of PL is not clear at present. Furthermore, it was confirmed that GaAs grows uniformly on AlGaAs layers even at 850 • C (not shown here), which is inconsistent with the results for growth on GaAs as describe above and reported previously [5]. This is not clear either, but one of the reason for this discrepancy is thought to be in the difference of initial nucleation of GaAs on between GaAs and AlGaAs surfaces.…”

“…In the case of SA-MOVPE growth on (111)B GaAs, nanostructures surrounded by vertical or inclined {110} facets are formed depending on the growth conditions, which makes this approach attractive and powerful to form quantum dots [1], hexagonal structures [2], and Kagome-lattice structures [3] Recently, we have reported on the SA-MOVPE growth on (111)B substrates for the applications to the photonic crystals (PhCs), which are the periodic structure of dielectric materials with their period (or lattice constant) Preprint submitted to Physica Ea close to the light wavelength. Formation of the air-hole array of GaAs [4,5], and pillar arrays of InGaAs [6] and InP [7] with a down to 0.4 µm have been reported. This is motivated by an early study by Hamano et al [8], where they grew hexagonal pillar arrays of GaAs on masked (111)B substrate with hexagonal opening areas.…”

Fabrication and characterization of GaAs two-dimensional air-hole arrays on GaAs (111)A substrates using selective-area MOVPE

“…4(a). Similar phenomena have already been observed in air-hole type SA-MOVPE on (1 1 1)B substrates [8,9]. In three2 1 1 corners (called B corners here), (1 1 1)B facets form and these suppress LOG because the growth rate of (1 1 1)B surfaces is low at low growth temperature.…”

“…We have already formed the shortest 400-nm-pitch hexagonal air-hole array, which is highly uniform with conventional SA-MOVPE and flow-rate modulation epitaxy [8,9]. However, we could not fabricate PhCs with an aspect ratio thicker than 0.3 (structure height; h/ period; a), although 2D air-hole type PhCs need more than a 0.6 aspect ratio in slab thickness for vertical optical confinement [10].…”