Mesa Shape Research Articles

Effects of pressure and temperature on epitaxial growth of InP on non-planar substrates using OMVPE

The effects of pressure and temperature on the epitaxial growth of InP on the mesastructured substrate have been investigated using OMVPE. At 550° C and 700 Torr, the reverse-mesa profile was observed. As the pressure decreases, the epitaxial growth profile changes from the reverse-mesa shape to the mesa shape. As the growth temperature increases, the growth profile follows the mesa-structured substrate even at high growth pressure. We propose that two major factors contributed to the formation of the reverse-mesa shape at low temperature and high pressure. We can explain the pressure effects on the epitaxial growth profile with these two factors at all growth temperatures ranging from 550 to 650° C. One factor is the growth rate enhancement on the (111)A facet compared to the growth rate on the (001) facet at low growth temperature, the other is the deficiency of constituent at the recess region of the epitaxial layer caused by reduced gas phase diffusivity at high pressure.

MOVPE regrowth of semi-insulating InP around reactive ion etched laser mesas

Semi-insulating iron doped InP was grown with MOVPE around reactive ion etched laser mesas without using any wet etchant to optimise the mesa shape or to form a mask overhang. To achieve good planarity and selectivity, growth was performed at high temperature and low pressure. The resulting 3 dB modulation bandwidth of the buried heterostructure laser was 7.9 GHz at 10.5 mW.

Effect of mesa shape on the planarity of InP regrowths performed by atmospheric pressure and low pressure selective metalorganic vapor phase epitaxy

The effect of mesa shape on the planarity of InP regrowths produced by atmospheric pressure and low pressure (0.1 atm) selective (SiO2 masked) metalorganic vapor phase epitaxy (MOVPE) is investigated. We find that for two separate atmospheric pressure reactor configurations (vertical and horizontal with a factor of 4 difference in growth rate), relatively planar regrowths are reproducibly obtained only when the mesa is non-reentrant, that is, with the narrowest portion of the mesa at the top in contact with the mask. For reentrant mesas grown at atmospheric pressure, the non-planarity is characterized by a large lateral growth rate at the top of the mesa just underneath the mask and by a very small growth rate underneath the volume of large lateral growth, the combination of which results in deep trenches on the side of the mesa and mask overgrowth from the edges. On the other hand, selective MOVPE at low pressure results in planar regrowths on the same reentrant mesas that had produced extremely non-planar regrowths during atmospheric pressure growth.

Selective growth of InP on patterned, nonplanar InP substrates by low-pressure organometallic vapor phase epitaxy

The effects of indium sources, mask materials and etched mesa profiles on growth mor-phology of Fe-doped semi-insulating InP on patterned, nonplanar InP substrates were studied for low-pressure organometallic vapor phase epitaxy (OMVPE). The presence or absence of polycrystalline InP layers deposited on the mask was found to depend on the indium source but not on the mask material. Trimethylindium was found to be the preferable indium source for prevention of polycrystalline InP deposits on the mask. The etched mesa shape was found to dominate the final geometry of the OMVPE re-grown InP layer. Inclusion of an interfacial layer of 1.16 µm bandgap wavelength InGaAsP between the dielectric mask and InP substrate produces a favorable mesa shape by con-trolling the level of undercut during mesa etching, so as to form a smooth mesa profile. After selective regrowth of InP over the resulting mesa, a planar surface is typically achieved for mesa stripes with a mask overhang length as long as 2.6 µm and a mesa height as high as 4 µm.

Low-temperature CW operation of GaInAsP/InP surface-emitting laser with circular buried heterostructure

The first CW operation of a GaInAsP surface-emitting laser has been demonstrated at 77 K. The active region was made to form a 15 μm-diameter circular mesa shape and was buried with p—n current-confining layers. The minimum CW threshold current was 19 mA at 77 K, and single-longitudinal-mode oscillation has been achieved.