Arsenide nanowire based quantum materials for advanced photonics

Abstract

This work concentrates on hybrid structures based on arsenic-containing nanowires, with a focus on material growth, structural regulation, performance characterization, and device construction, in order to obtain quantum heterostructures with excellent performance near the telecommunication characteristic wavelength. Specifically, it includes the following work: We first study the growth of InAs NWs and GaAs NWs. Based on the full understanding of the selective area growth method, the importance of the appropriate oxide layer on the surface of the silicon wafer for nanowire growth is explained. The two-step growth method is demonstrated to realize the growth of GaAs NWs, and the droplet assisted growth method is also proposed to achieve the growth of InAs NWs. For the InAs nanowires, after the successful growth of vertically InAs NWs standing on silicon substrate, the TEM results show a mixed phase of WZ and ZB, the PL results show emissions both from transition of BtB and type-II alignment. The built-in electric field formed in InAs NWs on p-type substrate leads to carrier assembling around the WZ-on-ZB interface, thus affected the emission feature. By carefully tuning FRV/III and FSb, InAsSb NWs with different Sb content have been obtained. The crystalline phases regulation and luminescence properties are clearly revealed as a function of Sb incorporation via detailed measurements and analysis (including TEM, temperature-sweeping PL, power-sweeping PL) on a series of InAsSb samples. InAsSb NWs with Sb incorporation of up to 19% have been obtained by suppressing the Sb surfactant effect, and the emission wavelength is successfully extended to 5.1 µm covering the entire MWIR band. This study opens the way to fabricate next-generation devices using InAsSb NWs, such as highly sensitive silicon-based room-temperature infrared photodetectors operating in MWIR and LWIR, by combining the advantages of III-V semiconductors. InAs/AlSb core–shell nanowire heterostructure is realized by molecular beam epitaxy and they also exhibit remarkable radiative emission efficiency, which is attributed to efficient surface passivation and quantum confinement induced by the shell. A highperformance core–shell nanowire phototransistor is also demonstrated with negative photoresponse. It has a dark current two orders of magnitude smaller and a sixfold improvement in photocurrent signal-to-noise ratio, in comparison with simple InAs nanowire phototransistor. InAs/InGaAs core-shell NWs are also obtained by growing the shell layer after the InAs stem. Due to the introduction of Ga, nanowires exhibit a mixed growth path of core-shell and axial heterostructure. The EDS analysis implies that Ga exhibits stronger incorporation in the shell growth. The PL results show a bimodal emission with a main peak energy of approximately 0.425 eV, with a very stable temperature profile. GaAs NWs were grown via VLS mode, and their optical properties were studied. The temperature and excitation scanning PL results show that the emission mainly comes from the transition of type-II alignment. The formation of the heterojunction after the introduction of Sb element was confirmed under the premise of maintaining the axial growth. The embedding of multiple GaAsSb nano disks is realized, with the emission wavelength increased to 1 µm, and the offset of conduction band of GaAs/GaAsSb is estimated to be about 53 meV. In addition, the embedding of ultra-thin GaAsSb nano disk is also successfully obtained associated with novel phenomenon of phase tuning.