Atomic hydrogen-assisted selective MBE growth of hexagonal InGaAs ridge quantum wire networks having a high density of giga-nodes/cm2

Successful growth of high-density hexagonal InGaAs ridge quantum wire (QWR) networks by an atomic hydrogen (H*)-assisted selective MBE technique is reported. As the templates, periodic hexagonal patterns with a pitch of 300 nm, consisting of <1~10>- and <510>-oriented mesa stripes, were prepared on [001] InP substrates by electron beam lithography and wet chemical etching. Then, InGaAs and InAlAs ridge structures were grown under H* irradiation, and they were characterized by SEM and AFM measurements. Although H* irradiation significantly improved facet flatness in both cases, InAlAs ridges were found to be better for QWR growth. By supplying InAlAs/InGaAs/InAlAs materials on the InAlAs ridge structure, a hexagonal network, consisting of embedded InGaAs QWRs and having a node density of 1 ×10⁹ cm^-2 could be successfully realized. Intense and narrow PL peaks from the network indicated high spatial uniformity and high crystalline quality of QWRs.