Alternating InAsP/InP heterostructure nanowires grown with tertiary-butyl chloride

We investigated alternating InAsP/InP nanowires grown by using reactive tertiary-butyl chloride (TBCl) on InP(111)B for optical device applications. The sequence of short InAsP growth, no growth with TBCl supply, and InP growth was repeated 100 times. The purpose of TBCl supply between the InAsP and InP growth was to enhance the diffusion of adsorbed arsenic species and remove excess arsenic species on nanowire sidewalls. A remarkably sharp hetero-interface from InAsP to InP was observed, while that from InP to InAsP was broad. From considerations with a simulation of the diffusion of adsorbed species in the growth process, a long residence time for adsorbed arsenic species and short residence time for adsorbed phosphorous species during TBCl supply between InAsP and InP growth cause the gradual increase of arsenic content in the InAsP layer. At the initiation of the next InP growth, a large amount of phosphorous species rush to the surface. This results in the immediate creation of the InP section, which makes the hetero-interface from InAsP to InP sharp. For this heterostructure nanowire, room-temperature photoluminescence up to a wavelength of 1.6 mu m and exciton-like emissions at low temperature of 4 K were observed.