A review on electronic and optical properties of silicon nanowire and its different growth techniques

Abstract

Electronic and optical properties of Silicon Nanowire (SiNW) obtained from theoretical studies and experimental approaches have been reviewed. The diameter dependency of bandgap and effective mass of SiNW for various terminations have been presented. Optical absorption of SiNW and nanocone has been compared for different angle of incidences. SiNW shows greater absorption with large range of wavelength and higher range of angle of incidence. Reflectance of SiNW is less than 5% over majority of the spectrum from the UV to near IR region. Thereafter, a brief description of the different growth techniques of SiNW is given. The advantages and disadvantages of the different catalyst materials for SiNW growth are discussed at length. Furthermore, three thermodynamic aspects of SiNW growth via the vapor-liquid-solid mechanism are presented and discussed.

Keywords: Bandgap; Chemical Vapour Deposition (CVD); Molecular Beam Epitaxy (MBE); Optical absorption; Reflectance; Silicon Nanowires (SiNWs).

Figure 1

Histogram of silicon “whisker” and “nanowire” publications. Source: ISI Web of Knowledge (SM).

Figure 2

Band gap as a function of the [100] silicon nanowire diameter for various surface terminations. (a) DFT calculations within GGA-PBE. (b) Results from a density-functional tightbinding (DFTB) parameterization.

Figure 3

Total reflectance data from integrated sphere measurements for an 11 μm thick solid Si thin film and nanowire film on glass substrate (Tsakalakos et al.2007)

Figure 4

Value of absorption on samples with a-Si:H thin film, NW arrays and NC arrays (a) Measured, (b) Calculated over a large range of wavelengths at normal incidence; (c) Measured (d) Simulated for different angle of incidence (at wavelengthλ= 488 nm) (Zhu et al.2009).

Figure 5

Schematic of the VLS growth mechanism (a) Catalytic liquid alloy (b,c) Successive growth of nanowire.

Figure 6

Schematics of experimental setup for nanowire growth using CVD method.

Figure 7

Schematics of experimental setup for silicon nanowire growth by evaporation of SiO.

Figure 8

Schematics of experimental setup for silicon nanowire growth by MBE.

Figure 9

Schematics of experimental setup for silicon nanowire growth by Laser Ablation method.

Figure 10

Oxidation of silicon surface under deposited metal.

Figure 11

Formation of silicon nanowires by electroless metal deposition.