GaAs Nanowires: From Manipulation of Defect Formation to Controllable Electronic Transport Properties

Abstract

Reliable control in the crystal quality of synthesized III-V nanowires (NWs) is particularly important to manipulate their corresponding electronic transport properties for technological applications. In this report, a "two-step" growth process is adopted to achieve single-crystalline GaAs NWs, where an initial high-temperature nucleation process is employed to ensure the formation of high Ga supersaturated Au7Ga3 and Au2Ga alloy seeds, instead of the low Ga supersaturated Au7Ga2 seeds observed in the conventional "single-step" growth. These two-step NWs are long (>60 μm) and thick (>80 nm) with the minimal defect concentrations and uniform growth orientations. Importantly, these NWs exhibit p-type conductivity as compared to the single-step grown n-type NWs for the same diameter range. This NW conductivity difference (p- versus n-channel) is shown to originate from the donor-like crystal defects, such as As precipitates, induced by the low Ga supersaturated multicrystalline Au7Ga2 alloy seeds. Then the well-controlled crystal quality for desired electronic properties is further explored in the application of large-scale p-type GaAs NW parallel array FETs as well as the integration of both p- and n-type GaAs NWs into CMOS inverters. All these illustrate the successful control of NW crystal defects and corresponding electronic transport properties via the manipulation of Ga supersaturation in the catalytic alloy tips with different preparation methods. The understanding of this relationship between NW crystal quality and electronic transport properties is critical and preferential to the future development of nanoelectronic materials, circuit design, and fabrication.

Surfactant-assisted chemical vapour deposition of high-performance small-diameter GaSb nanowires

“…Moreover, another typical III-V semiconductor (that is, GaAs) NW system is employed to demonstrate the generality of this adopted surfactant-assisted growth method. As reported in the previous work 52 , GaAs NWs with relatively short length (B3 mm) and large-diameter distribution (76.1 ± 49.9 nm) were obtained by the solid-source CVD method utilizing 12-nm-thick Au film as the catalyst without sulfur. On the contrary, by adopting the sulfur surfactant process, the obtained GaAs NWs become much thinner with a narrower diameter distribution of 36.9 ± 8.5 nm, as shown in Fig.…”

High-Performance GaAs Nanowire Solar Cells for Flexible and Transparent Photovoltaics

“…On the other hand, the grown GaAs NWs are single crystalline with minimal crystal defects observed due to the relatively higher Ga supersaturation in Au catalytic seeds during the growth process as reported in our previous study. 11,14 Also, since no dopant is utilized here, there would not be any impurity centers for the electron/holes recombination. All these minimized defects and scattering centers would then contribute to the longer minority lifetime which is favorable for efficient photo-induced electron/hole separation and collection.…”

“…11,12 The Au catalyst film (thermally deposited onto 50 nm SiO 2 /Si, with the dimension of 5 cm long and 1 cm wide) is placed in the downstream zone of a two-zone furnace, annealed into nanoparticles at 800 o C for 10 min and then cooled down to 650 o C under the pressure of ~ 1 torr in H 2 atmosphere (99.99% purity, flow at 100 standard cubic centimeters per minute, sccm). Then, the GaAs powders are held in a boron nitride crucible located in the upstream zone, which is heated at 800-900 o C. The evaporated precursors are transported by H 2 flow to the Au catalyst.…”

ZnO Nanofiber Thin‐Film Transistors with Low‐Operating Voltages

“…For example, CVD has been widely employed for the growth of 1D semiconductor nanostructures, [17,18] in which this technique is still far from being compatible with the large-scale manufacturing platform due to the rather high fabricating cost, rigorous process control, low production throughput, and complicated subsequent device fabrication scheme. [9,19] Although hydrothermal methods are seem to be the simple process and capable to produce large amounts of 1D nanomaterials with the relatively low cost, they are challenging to precisely control the diameter, morphology, and crystal structure of the nanomaterials obtained, seriously influencing their chemical and physical properties, eventually limiting their practical utilizations. [13,20] In general, electrospinning is well accepted to its simplicity and versatility to yield organic, inorganic or composite nanofibers (NFs).…”

“…[1][2][3][4][5][6][7] Among these 1D nanomaterials, many novel synthesis techniques have then been developed, including chemical vapor deposition (CVD), [8][9][10] hydrothermal methods, [11][12][13] and template-assisted electrodeposition, etc; [14][15][16] however, all of these fabrication schemes come with different process-related disadvantages. For example, CVD has been widely employed for the growth of 1D semiconductor nanostructures, [17,18] in which this technique is still far from being compatible with the large-scale manufacturing platform due to the rather high fabricating cost, rigorous process control, low production throughput, and complicated subsequent device fabrication scheme.…”