Direct Synthesis of Hyperdoped Germanium Nanowires

Abstract

A low-temperature chemical vapor growth of Ge nanowires using Ga as seed material is demonstrated. The structural and chemical analysis reveals the homogeneous incorporation of ∼3.5 at. % Ga in the Ge nanowires. The Ga-containing Ge nanowires behave like metallic conductors with a resistivity of about ∼300 μΩcm due to Ga hyperdoping with electronic contributions of one-third of the incorporated Ga atoms. This is the highest conduction value observed by in situ doping of group IV nanowires reported to date. This work demonstrates that Ga is both an efficient seed material at low temperatures for Ge nanowire growth and an effective dopant changing the semiconductor into a metal-like conductor.

Electrical characterization and examination of temperature-induced degradation of metastable Ge0.81Sn0.19nanowires

“…Intrinsic Ge NWs grown by Au-seeding show a strong dependence on the temperature and an increase of resistivity by several orders of magnitude upon cooling. In contrast, the Ge 0.81 Sn 0.19 NW's resistivity appear to be almost independent on temperature, similar to hyperdoped Ge 0.97 Ga 0.03 NWs 11 as described in literature. A more detailed view reveals an increase in resistivity with decreasing temperatures (inset Fig.…”

“…3 illustrates the resistivity-dependence on temperature variation in the range from 298 to 10 K, which was investigated in four-point configuration. At room temperature, resistivity values of Ge 0.81 Sn 0.19 NWs (∼1 × 10 –4 Ω m) are typically 2 orders of magnitude lower than for intrinsic Ge (∼9 × 10 –3 Ω m), 58 but approximately two orders of magnitude higher than for hyperdoped Ge 0.97 Ga 0.03 NWs (∼3 × 10 –6 Ω m) 11 as shown in Fig. 3 .…”

Direct Growth of Si, Ge, and Si–Ge Heterostructure Nanowires Using Electroplated Zn: An Inexpensive Seeding Technique for Li‐Ion Alloying Anodes

“…EDX elemental mapping of NWs grown using type B catalysts usually show detectable quantities of the catalyst being incorporated into the NW, [47,48] thereby introducing impurities that can have significant effects on the NWs electrical and photoelectric properties. [11,49] EDX elemental mapping of the Si, Ge, and Si-Ge axial heterostructure NWs ( Figure S7, Supporting Information) shows that while Zn was detected in the Ge NW, no detectable amount of Zn is incorporated into the Si NW. Higher-resolution elemental mapping of a Zn-seeded Si NW (Figure 4a) was performed using a four-detector EDX system.…”

Solution-based low-temperature synthesis of germanium nanorods and nanowires

“…This model has been discussed for the incorporation of Al in Si nanowires where unusually high Al concentrations in the Si nanowire body have been observed [31, 34]. The Ga content in the here presented NRs is lower than in Ga-seeded NWs grown by VLS (3.51 ± 0.29 at.%) at the same temperature, which could be attributed to a higher probability of Ga trapping in crystal growth with higher growth rates [27]. Shifts of reflections in the XRD pattern should not be expected due to the similarity in size of Ga and Ge [35].…”

“…Even though the amount of Ga incorporation is very high (8–10%), only very low donor activity of the well-known p-dopant Ga has been observed [25]. In contrast, we recently reported Ga hyperdoping for VLS-grown Ge NWs with very high concentration of electronically active p-donor values of ~ 5×10 20 cm −3 [27]. According to the binary Ge-Ga phase diagram, the Ga/Ge eutectic is very close to the melting point of gallium (29.8 °C), illustrating that even lower temperatures than the reported 210 °C could be considered for the Ge nanostructure growth via the SLS mechanism (Fig-S1 in the Supplementary Information; SI) [28].…”