Theory of MBE Growth of Nanowires on Reflecting Substrates

Selective area growth (SAG) of III-V nanowires (NWs) by molecular beam epitaxy (MBE) and related epitaxy techniques offer several advantages over growth on unpatterned substrates. Here, an analytic model for the total flux of group III atoms impinging NWs is presented, which accounts for specular re-emission from the mask surface and the shadowing effect in the absence of surface diffusion from the substrate. An expression is given for the shadowing length of NWs corresponding to the full shadowing of the mask. Axial and radial NW growths are considered in different stages, including the stage of purely axial growth, intermediate stage with radial growth, and asymptotic stage, where the NWs receive the maximum flux determined by the array pitch. The model provides good fits with the data obtained for different vapor–liquid–solid and catalyst-free III-V NWs.

Асимптотическая стадия роста автокаталитических III-V нитевидных нанокристаллов методом молекулярно-пучковой эпитаксии

A new analytic theory is developed for asymptotic stage of self-catalyzed growth of III-V nanowires (NWs) by molecular beam epitaxy (MBE), where NWs collect all group III atoms deposited from vapor. The shadowing NW length is derived which corresponds for the full shadowing of the substrate surface in MBE. The NW length and radius are derived depending on the effective deposition thickness and MBE growth parameters. It is shown that the NW length increases, and their length decreases with decreasing the array pitch and increasing the V/III flux ratio.

Features of the MBE growth of nanowires with quantum dots on the silicon surface

The development of a new semiconductor element base is necessary to create a new generation of applications. At present time, the synthesis of high-quality hybrid nanostructures based on III-V quantum dots in the body of nanowires of a wide range of material systems is an urgent and important task. In work hybrid III-V nanostructures based on QDs in the body of NWs in GaP/GaAs and AlGaP/InGaP material systems were synthesized in on silicon substrates and their physical properties were investigated.

MBE growth of AlGaAs/Ge/AlGaAs core-shell nanowire

Heterostructured AlGaAs/Ge/AlGaAs core-multishell nanowires having hexagonal crystal structure were synthesized by molecular beam epitaxy. Formation of 2-3 nm Ge quantum well structure was demonstrated. Raman characterization revealed a 200 cm−1 peak corresponded to hexagonal phases of germanium.

III-V nanowires with quantum dots: MBE growth and properties

We demonstrate growth of AlGaAs NWs with GaAs QDs and InP NWs with InAsP QDs on silicon substrates. Results of GaAs QDs optical properties study have shown that these objects are sources of single photons. In case of InP NWs with InAsP QDs, the results showed that ~ 100% of homogeneously oriented NWs were formed with good optical quality of this system on a Si(111). PL spectrum peak near 1.3 μm indicates that such system is promising for optoelectronic devices.

Thermopower of Gadolinium Nitride

The following is a report on the thermopower of Gadolinium Nitride. It begins with a discussion of the theory of thermopower. It progresses through simulation, design, and construction of the thermopower measurement stage. It discusses the MBE growth process used to produce the thin-film samples, as well as the subtleties and difficulties associated with making thermopower measurements in situ. It then presents the results of our investigation, and closes with a discussion on possible directions for future work.